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Python数据分析(中英对照)·Random Choice 随机选择

通常,当我们使用数字时,偶尔也会使用其他类型的对象,我们希望使用某种类型的随机性。 Often when we’re using numbers, but also,occasionally, with other types of objects,we would like to do some type of randomness. 例如,我们可能想要实现一个简单的随机抽样过程。 For example, we might want to implement a simple random sampling process. 为此,我们可以使用随机模块。 To this end, we can use the random module. 所以,我们的出发点是,再次导入这个模块,random。 So the starting point is, again, to import that module, random. 让我们考虑一个简单的例子,其中列表中包含一组数字,我们希望从这些数字中随机统一选择一个。 Let’s think about a simple example where we have a set of numbers contained in a list,and we would like to pick one of those numbers uniformly at random. 在本例中,我们需要使用的函数是random.choice,在括号内,我们需要一个列表。 The function we need to use in this case is random.choice,and inside parentheses, we need a list. 在这个列表中,我将只输入几个数字——2、44、55和66。 In this list, I’m going to just enter a few numbers– 2, 44, 55, and 66. 然后,当我运行随机选择时,Python会将其中一个数字返回给我。 And then when I run the random choice, Python returns one of these numbers back to me. 如果我重复同一行,我会得到一个不同的答案,因为Python只是随机选取其中一个对象。 If I repeat the same line, I’m going to get a different answer,because, again, Python is just picking one of those objects at random. 关于随机选择方法,需要了解的一个关键点是Python并不关心所使用对象的基本性质 A crucial thing to understand about the random choice method is that Python doesn’t care about the fundamental nature of the objects that 都包含在该列表中。 are contained in that list. 这意味着,不用数字,我也可以从几个字符串中选择一个。 What that means, instead of using numbers,I could also be choosing one out of several strings. 让我们看看这是怎么回事。 So let’s see how that might work. 我要回到我的清单上。 I’m going to go back to my list. 我只想在这里包括三个短字符串。 I’m just going to include three short strings here. 让我们只做“aa”,“bb”和“cc” Let’s just do "aa," "bb," and "cc." 我可以让Python随机选择其中一个。 I can ask Python to pick one of these uniformly at random. 因此Python并不关心这些对象的性质。 So Python doesn’t care about the nature of these objects. 对于任何类型的对象,随机的工作方式都是一样的。 Random works just the same way for any type of object.

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Python数据分析(中英对照)·Simulating Randomness 模拟随机性

Many processes in nature involve randomness in one form or another. 自然界中的许多过程都以这样或那样的形式涉及随机性。 Whether we investigate the motions of microscopic molecules or study the popularity of electoral candidates,we see randomness, or at least apparent randomness, almost everywhere. 无论我们研究微观分子的运动,还是研究候选人的受欢迎程度,我们几乎处处都能看到随机性,或者至少是明显的随机性。 In addition to phenomena that are genuinely random,we often use randomness when modeling complicated systems 除了真正随机的现象外,我们在建模复杂系统时经常使用随机性 to abstract away those aspects of the phenomenon for which we do not have useful simple models. 将我们没有有用的简单模型的现象的那些方面抽象出来。 In other words, we try to model those parts of a process that we can explain in relatively simple terms,and we assume, true or not, that the rest is noise. 换句话说,我们试图对过程中那些我们可以用相对简单的术语解释的部分进行建模,并且我们假设,不管是真是假,其余部分都是噪音。 To put this differently, we model what we can,and whatever it happens to be left out, we attribute to randomness. 换一种说法,我们对我们能做的事情进行建模,不管发生什么,我们都将其归因于随机性。 These are just some of the reasons why it’s important to understand how to simulate random numbers and random processes using Python. 这些只是理解如何使用Python模拟随机数和随机进程很重要的一些原因。 We have already seen the random module. 我们已经看到了随机模块。 We will be using that to simulate simple random processes,but we’ll also take a look at some other tools the Python has to generate random numbers. 我们将使用它来模拟简单的随机过程,但我们还将看看Python生成随机数的其他一些工具。 Let’s see how we can use the random choice function to carry out perhaps the simplest random process – the flip of a single coin. 让我们看看如何使用随机选择函数来执行可能是最简单的随机过程——抛一枚硬币。 I’m first going to import the random library. 我首先要导入随机库。 So I type import random. 所以我输入import random。 Then we’ll use the random choice function. 然后我们将使用随机选择函数。 We first need parentheses. 我们首先需要括号。 And in this case, we need some type of a sequence, here a list,to contain the elements of the sequence. 在这种情况下,我们需要某种类型的序列,这里是一个列表,来包含序列的元素。 I’m going to go with two strings, H for heads and T for tails. 我要用两根弦,H代表正面,T代表反面。 If I now run this code, Python will pick one of the

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