matplotlib如何知道在此代码中显示什么? [英] How does matplotlib knows what to display in this code?

问题描述

下面的python代码将显示直方图和散点图的成对图.

The python code below will display pair plots of histogram and scatter-plots.

import pandas as pd
import matplotlib.pyplot as plt

from sklearn import datasets

iris_dataset = datasets.load_iris()
X = iris_dataset.data
Y = iris_dataset.target

iris_dataframe = pd.DataFrame(X, columns=iris_dataset.feature_names)
# create a scatter matrix from the dataframe, color by y_train
grr = pd.scatter_matrix(iris_dataframe, c=Y, figsize=(15, 15), marker='o',
                        hist_kwds={'bins': 20}, s=60, alpha=.8)

plt.show()

让我感到困惑的是，plt.show()如何知道要显示什么?在代码plt中的任何位置都没有看到grr被分配. plt如何神奇地知道要显示什么?

What puzzles me is how does plt.show() know what to display? grr was not seen to be assigned anywhere in the code into plt. How does plt magically knows what to display?

推荐答案

Pandas使用matplotlib创建其图.完整的图已经通过pandas.scatter_matrix命令创建.

Pandas uses matplotlib to create its plots. The complete plot is already created by the pandas.scatter_matrix command.

pandas.scatter_matrix的返回是matplotlib轴的数组.创建后可用于调整图.
但是，这不是必需的，因为完整的图已经作为matplotlib图形存在.

The return of pandas.scatter_matrix is an array of matplotlib axes. This can be used to adjust the plot after creation.
However, this is not necessary as the complete plot already exist as a matplotlib figure.

调用plt.show()时，会简单地绘制matplotlib状态机中存在的任何图形.由于存在一个图形(= pandas.scatter_matrix创建的图形)，因此将显示它.

When calling plt.show() any figure present in the matplotlib state machine is simply plotted. Since there is a figure present (=the one created by pandas.scatter_matrix), it will be shown.

这篇关于matplotlib如何知道在此代码中显示什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！