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    Python数据分析(中英对照)·Introduction to Matplotlib and Pyplot-Matplotlib 和 Pyplot 介绍

    Matplotlib is a Python plotting library that produces publication-quality figures. Matplotlib是一个Python绘图库,用于生成出版物质量的图形。 It can be used both in Python scripts and when using Python’s interactive mode. 它既可以在Python脚本中使用,也可以在使用Python的交互模式时使用。 Matplotlib is a very large library, and getting to know it well takes time. Matplotlib是一个非常大的库,了解它需要时间。 But often we don’t need the full matplotlib library in our programs,and this is where Pyplot comes in handy. 但是我们的程序中通常不需要完整的matplotlib库,这就是Pyplot的用武之地。 Pyplot is a collection of functions that make matplotlib work like Matlab,which you may be familiar with. Pyplot是一组函数,使matplotlib像Matlab一样工作,您可能熟悉这些函数。 Pyplot is especially useful for interactive work,for example, when you’d like to explore a dataset or visually examine your simulation results. Pyplot对于交互式工作尤其有用,例如,当您希望浏览数据集或直观地检查模拟结果时。 We’ll be using Pyplot in all our data visualizations. 我们将在所有数据可视化中使用Pyplot。 Pyplot provides what is sometimes called a state machine interface to matplotlib library. Pyplot为matplotlib库提供了有时称为状态机的接口。 You can loosely think of it as a process where you create figures one at a time,and all commands affect the current figure and the current plot. 您可以粗略地将其视为一个一次创建一个地物的过程,所有命令都会影响当前地物和当前绘图。 We will mostly use NumPy arrays for storing the data that we’d like to plot, but we’ll occasionally use other types of data objects such as built-in lists. 我们将主要使用NumPy数组来存储要绘制的数据,但偶尔也会使用其他类型的数据对象,如内置列表。 As you may have realized, saying matplotlib.pyplot is kind of a mouthful, and it’s a lot to type too. 正如您可能已经意识到的那样,说matplotlib.pyplot有点口齿不清,而且打字也很费劲。 That’s why virtually everyone who uses the library imports it as plt, which is a lot shorter. 这就是为什么几乎所有使用该库的人都将其作为plt导入,而plt要短得多。 So to import the library, we will type the following– import matplotlib.pyplot as plt. 因此,要导入库,我们将键入以下内容–import matplotlib.pyplot as plt。 Now we are ready to start our plotting. 现在我们准备开始我们的阴谋。 A basis but very useful command is the plt plot function, which can be used to plot lines and markers. plt plot函数是一个基本

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    Python数据分析(中英对照)·Customizing Your Plots-自定义绘图

    There are a few important elements that can be easily added to plots. 有几个重要元素可以轻松添加到绘图中。 For example, we can add a legend with the legend function. 例如,我们可以使用图例功能添加图例。 We can adjust axes with axis, where axis is spelled A-X-I-S. 我们可以用axis调整轴,其中axis拼写为A-X-I-S。 We can set axis labels using xlabel and ylabel. 我们可以使用xlabel和ylabel设置轴标签。 And we can save a figure using savefig. 我们可以使用savefig保存一个图形。 In that case, the file format extension specifies the format of the file,such as pdf or png. 在这种情况下,文件格式扩展名指定文件的格式,如pdf或png。 Let’s now add these elements to our previous plot. 现在,让我们将这些元素添加到上一个绘图中。 I’m going to construct this plot in the editor. 我将在编辑器中构建这个情节。 So I’m going to take my first line and place that in the editor. 所以我要把我的第一行放到编辑器中。 Then I’m going to take my second line and just copy paste that in the editor. 然后,我将获取第二行,并将其复制粘贴到编辑器中。 If I want to construct the full plot, I’m going to find my definition of x, so we have a full example,x was defined here. 如果我想构造完整的图,我会找到我对x的定义,所以我们有一个完整的例子,x在这里被定义。 Then we had definitions of y1, which was given here. 然后我们有了y1的定义,这里给出了。 And we have also our definition of y2, which is here. 我们还有y2的定义,在这里。 This is the plot that we’ve been looking at so far. 这是我们到目前为止一直在看的情节。 I’m going to start by adding axes labels to this plot. 我将首先向这个图中添加轴标签。 I’m going to type plt.xlabel. 我要输入plt.xlabel。 And we’ll just put it in an X for the x-axis. 我们把它放在X轴上。 And we can use the same idea for ylabel, in which case we’ll just call it Y. 我们可以对ylabel使用相同的想法,在这种情况下,我们将其称为Y。 If you’re familiar with LaTeX, which is the typesetting software often used in mathematical publications, you’ll be pleased to know that plt also knows LaTeX. 如果您熟悉LaTeX,这是数学出版物中经常使用的排版软件,您会很高兴知道plt也了解LaTeX。 If you’re not familiar with it, here’s a brief idea. 如果你不熟悉它,这里有一个简单的想法。 We can take a mathematical notation or a symbol like x,and we can put dollar signs around that. 我们可以用一个数学符号或者像x这样的符号,我们可以在它周围加上美元符号。 All this does is that it changes the appearance of x and y in your plot. 所有这一切只是改变了绘图中x

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    Python数据分析(中英对照)·Random Walks 随机游走

    This is a good point to introduce random walks. 这是引入随机游动的一个很好的观点。 Random walks have many uses. 随机游动有许多用途。 They can be used to model random movements of molecules, 它们可以用来模拟分子的随机运动, but they can also be used to model spatial trajectories of people, 但它们也可以用来模拟人的空间轨迹, the kind we might be able to measure using GPS or similar technologies. 我们可以用GPS或类似的技术来测量。 There are many different kinds of random walks, and properties of random walks 有许多不同种类的随机游动,以及随机游动的性质 are central to many areas in physics and mathematics. 是物理学和数学许多领域的核心。 Let’s look at a very basic type of random walk on the white board. 让我们看看白板上一种非常基本的随机行走。 We’re first going to set up a coordinate system. 我们首先要建立一个坐标系。 Let’s call this axis "y" and this "x". 我们把这个轴叫做“y”,这个叫做“x”。 We’d like to have the random walk start from the origin. 我们想让随机游动从原点开始。 So this is position 1 for the random walk. 这是随机游动的位置1。 To get the position of the random walker at time 1, we can pick a step size. 为了得到时间1时随机行走者的位置,我们可以选择一个步长。 In this case, I’m just going to randomly draw an arrow. 在这种情况下,我将随机画一个箭头。 And this gives us the location of the random walker at time 1. 这给了我们时间1的随机游走者的位置。 So this point here is time is equal to 0. 这里的时间等于0。 And this point here corresponds to time equal to 1. 这一点对应于等于1的时间。 We can take another step. 我们可以再走一步。 Perhaps in this case, we go down, say over here. 也许在这种情况下,我们下去,比如说在这里。 And this is our location for the random walker at time t is equal to 2. 这是时间t等于2时,随机游走者的位置。 This is the basic idea behind all random walks. 这是所有随机游动背后的基本思想。 You have some location at time t, and from that location 你在时间t有一个位置,从这个位置开始 you take a step in a random direction and that generates your location 你在一个随机的方向上迈出一步,这就产生了你的位置 at time t plus 1. 在时间t加1时。 Let’s look at these a little bit more mathematically. 让我们从数学的角度来看这些。 First, we’re going to start with the location of the random walk at time t 首先,我们从时间t的随机游动的位置开始 is equal to 0. 等于0。 So position x at time t is equal to 0 is whatever 所以时间t处的位置x等于0是什么 the location of the random walke

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