Python列表创建的技巧
《Effective Python》是Brett Slatkin撰写的一本涵盖59种写更好Python代码的具体方法的书籍。该书以随机访问的方式编写，每个主题都有独立的源代码。对于中级Python程序员来说，无论是工程师还是数据科学家，这是一个很好的资源，因为它涵盖了可以以任何顺序学习的广泛主题范围。
许多涵盖的主题非常适用于数据科学工作流。例如，它涵盖了遵循PEP8的Pythonic思维方式，PEP8是一个确保Python代码可读性的风格指南。它涵盖了函数、类和元类的最佳实践，这些在数据科学工作流中有重要用途。它还介绍了编写可读的列表、元组和字典推导式的最佳方法。这可以应用于诸如特征工程、数据预处理和数据后处理等任务。
推导式是一种以可读的方式从另一个列表中派生出一个列表的有用方法。《Effective Python》介绍了推导式的最佳实践（也适用于元组和字典）。它不建议使用map和filter，虽然它们可以实现与推导式相同的任务，但代码更繁琐，更难阅读。它还建议不要在推导式中使用多个表达式。最后，它建议对需要处理大量数据的推导式使用生成器。
在数据科学工作流中编写高效的Python可以确保用于诸如特征工程、数据预处理和数据后处理等任务的代码是高效且易于阅读的。效率和可读性使得数据科学和机器学习代码库更容易维护。代码越容易阅读，对其进行更改而不会引入错误就越容易。此外，了解执行任务的更有效方法（如列表推导式）最终有助于开发人员编写更有效的代码。
接下来我们将看到如何将三个有效的Python实践融入简单的数据科学工作流中。我们将看到使用列表推导式而不是map和filter可以提高可读性。我们还将看到将推导式限制为最多两个表达式可以确保代码清晰度。最后，我们将比较推导式和生成器在处理大量数据时的情况。
在这项工作中，我将在Deepnote中编写代码，这是一个协作的数据科学笔记本，可以轻松运行可重现的实验。我们将使用医疗保健费用数据集。该数据是可以自由使用、修改和共享的，遵循数据库内容许可证（DbCL：公共领域）。
使用列表推导式而不是map和filter
Map和filter是Python中的内置函数，提供了可以通过列表推导式实现的任务的便捷方式。为了演示这些技术之间的差异，我们将考虑两种常见的数据任务。具体来说，我们将展示如何使用map生成列的对数变换，然后展示如何使用列表推导式完成相同的任务。
首先，让我们转到Deepnote并创建一个新项目（如果您还没有帐户，可以免费注册）。
让我们创建一个名为“effective_python”的项目，并在此项目中创建一个名为“list_comp_generators”的笔记本。还可以将insurance.csv文件拖放到页面左侧标有“FILES”的面板上：
接下来，让我们导入pandas库并将数据读取到pandas数据帧中：
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">import pandas <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">as pd
df = pd.read_csv(<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">"insurance.csv")
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">然后让我们显示前五行数据：
df.head()
使用Map进行对数变换
我们首先考虑的列转换是对数变换。这是一种常用的技术，用于将偏斜的数据转换为近似正态分布的数据。我们可以使用map()函数来转换数据中的一列数字值。让我们使用map来对BMI值进行对数变换。我们将导入Numpy库并定义一个接受列表作为输入并返回对数变换元素列表的函数：
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">import numpy <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">as np
<span class="hljs-function" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;"><span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">def <span class="hljs-title" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(165, 218, 45); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">log_transform<span class="hljs-params" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(255, 152, 35); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">(input_list):
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">return np.log(input_list)
</span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-params" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(255, 152, 35); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-title" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(165, 218, 45); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-function" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">接下来，我们可以使用map将我们的函数应用于BMI列表。map函数接受我们将要应用的函数名称和一个可迭代对象（在我们的情况下是一个列表）：
output_list = map(function, list)
我们继续定义一个名为bmi_list的变量，并将BMI值列表存储在该变量中。然后，我们可以将我们的函数和列表传递给内置的map函数，并将结果存储在一个新列表中，我们将其称为bmi_lt_map。然后，我们需要定义一个新列来存储我们的转换列：
bmi_list = list(df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi'])
bmi_lt_map = list(map(log_transform, bmi_list))
df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi_lt_map'] = bmi_lt_map
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">请注意，这需要5行代码来完成：
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">import numpy <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">as np
<span class="hljs-function" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;"><span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">def <span class="hljs-title" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(165, 218, 45); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">log_transform<span class="hljs-params" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(255, 152, 35); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">(input_list):
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">return np.log(input_list)
bmi_list = list(df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi'])
bmi_lt_map = map(log_transform, bmi_list)
df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi_lt_map'] = bmi_lt_map
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-params" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(255, 152, 35); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-title" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(165, 218, 45); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-function" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">使用列表推导式进行对数变换
让我们看看如何使用列表推导式可以帮助我们以更易理解的代码实现相同的功能：
df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi_lt_listcomp'] = [np.log(bmi) <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for bmi <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in list(df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi'])]
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">我们看到我们可以只用两行代码完成完全相同的事情。而且更容易阅读。值得注意的是，直接将对数变换应用于数据帧列也很紧凑且易于阅读，尽管对于更复杂的转换可能不可行。
df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi_lt_direct'] = np.log(df[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'bmi'])
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">避免在列表推导式中使用两个以上的表达式
假设我们有一个由分类机器学习模型生成的预测概率列表的列表：
my_predictions = [[<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8], [<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.3, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.1, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.9], [<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">1.0, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.7]]
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">我们可以使用列表推导式将这个列表的列表转换为一个单一的列表（我们可以“扁平化”列表）：
flattened_predictions = [prob <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for row <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in my_predictions <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for prob <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in row]
print(flattened_predictions)
</span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">[<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.3, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.1, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.9, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">1.0, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.7]
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">这是一个包含两个for循环的列表推导式。这是使用两个传统for循环的易读替代方法：
flat_fl = []
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for row <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in my_predictions:
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for prob <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in row:
flat_fl.append(prob)
print(flat_fl)
</span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">[<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.3, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.1, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.9, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">1.0, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.7]
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">列表推导式方法占用两行代码，而传统for循环占用5行代码！尽管列表推导式非常方便，易于阅读，但随着表达式超过两个，可读性和紧凑性迅速减弱。假设我们想生成一个包含标签“Yes”的列表，概率大于0.8，“Maybe”的概率在0.5到0.8之间，“No”的概率小于0.5的概率列表。我们可以使用列表推导式来实现：
ml_labels = [[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes' <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">if prob >= <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8 <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">else <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Maybe' <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">if (prob > <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5 <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">and prob < <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8) <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">else <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No' <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for prob <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in row] <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for row <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in my_predictions]
print(my_predictions)
print(ml_labels)
</span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">[[<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8], [<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.3, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.1, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.9], [<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">1.0, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.7]]
[[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes'], [<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes'], [<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Maybe']]
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">尽管这很紧凑，但很难阅读和理解。如果我们使用传统的for循环，尽管需要更多的代码行，但更容易理解：
fl_labels = []
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for row <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in my_predictions:
hold_list = []
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for prob <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in row:
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">if prob >= <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8:
hold_list.append(<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes')
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">elif (prob > <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5 <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">and prob < <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8):
hold_list.append(<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Maybe')
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">else:
hold_list.append(<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No')
fl_labels.append(hold_list)
print(my_predictions)
print(fl_labels)
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">[[<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.8], [<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.3, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.1, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.9], [<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">1.0, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.2, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.7]]
[[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes'], [<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes'], [<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Maybe']]
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">一个好的经验法则是避免在列表推导式中使用两个或更多表达式，包括for循环和条件。
用于大型输入的生成器表达式
虽然列表推导式非常有用，紧凑且易于理解，但对于大型输入，它们可能需要大量内存。用于大型输入的列表推导式的替代方法是生成器表达式。
生成器表达式将推导式和生成器结合在一起。它们非常适合大型输入，因为它们从表达式中逐个生成项目。要编写生成器表达式，我们只需使用括号()。假设我们有一个大型的分类预测概率列表。我们将使用Numpy的random.normal方法生成一个具有均值0.5和标准差0.1的合成列表，其中包含2亿个预测概率：
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">import numpy <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">as np
mu, sigma = <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.1
np.random.seed(<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">42)
probs = np.random.normal(mu, sigma, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">200000000)
print(probs[:<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">10])
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;">[<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.54967142 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.48617357 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.56476885 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.65230299 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.47658466 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.4765863
<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.65792128 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.57674347 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.45305256 <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.554256 ]
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">现在假设我们想使用列表推导式从中生成一个标签列表。我们将为大于0.5的概率分配一个标签“是”，并为小于0.5的概率分配一个标签“否”。
如果我们尝试在与列表推导式相同的单元格中打印前十个元素，会耗尽内存。
因此，我们需要在单独的单元格中执行：
print(prob_labels[:<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">10])
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;">[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes']
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">生成器表达式可以用于评估一个迭代器，该迭代器逐个生成项目，而不是整个表达式。这可以帮助避免内存分配问题：
prob_generator = (<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes' <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">if prob > <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0.5 <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">else <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No' <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for prob <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in probs)
probs_sublist = []
<span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">for i <span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">in range(<span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">0, <span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">11):
probs_sublist.append(next(prob_generator))
print(probs_sublist)
</span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-number" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(174, 135, 250); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-keyword" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(248, 35, 117); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">[<span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'Yes', <span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;" style="font-size: inherit;color: inherit;line-height: inherit;overflow-wrap: inherit !important;word-break: inherit !important;">'No']
</span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;"></span class="hljs-string" style="font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; color: rgb(238, 220, 112); word-wrap: inherit !important; word-break: inherit !important;">我们看到我们能够创建生成器对象并打印前十个元素，而不会遇到内存问题。
这篇文章中的代码可以在GitHub上找到。
https://github.com/spierre91/deepnote/blob/main/list_comp_generators.ipynb
结论
在本文中，我们讨论了通过Pythonic思维改进列表创建的一些有用方法。
首先，我们讨论了在与Python初学者协作时，应该使用列表推导式而不是map和filter，因为它更容易理解。
然后，我们介绍了在列表推导式中使用两个以上的表达式应该避免以最大化清晰度和可读性。
最后，我们展示了如何使用生成器表达式作为大型输入的列表推导式的替代方法。鼓励您将这些技巧应用到您自己的软件工程和机器学习项目中。
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原始发表：2024-03-26，如有侵权请联系 cloudcommunity@tencent.com 删除
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