pyplot的绘图转换为numpy矩阵

height_default, dpi_default= (4.8, 100)
    
fig = plt.figure()
plt.plot(x, y)
fig.canvas.draw()
fig_str = fig.canvas.tostring_rgb()
data = np.frombuffer(fig_str, dtype=np.uint8).reshape((int(height_default*dpi_default), -1, 3)) / 255.0

主要步骤为：
（1）创建 Figure
（2）在Figure中绘图，plot()、scatter()、imshow()…都行
（3）在canvas中绘制
（4）将canvas转换为「字符串」
（5）使用numpy.frombuffer()从「字符串」中读取数组，并用reshape()转换回矩阵

参考上一篇文章：避免pyplot出现Fail to allocate bitmap报错的方法

import matplotlib.pyplot as plt
import numpy as np


class plot_to_matrix:
    def __init__(self):
        self.width= 6
        self.height= 4
        self.dpi= 128
        self.fig_convert = plt.figure(figsize=(self.width, self.height), dpi=self.dpi)
        self.axes_convert = self.fig_convert.add_axes([0.16, 0.15, 0.75, 0.75])

    def plot_to_matrix(self, x, y):
        self.axes_convert.cla()
        self.axes_convert.plot(x, y)

        self.fig_convert.canvas.draw()
        fig_str = self.fig_convert.canvas.tostring_rgb()
        data = np.frombuffer(fig_str, dtype=np.uint8).reshape((self.height*self.dpi, -1, 3))/255.0
        return data

if __name__ == '__main__':
    x= np.linspace(0,1,100)
    y= np.sin(x*20)
    pm= plot_to_matrix()
    for i in range(1000):
        m= pm.plot_to_matrix(x, y)
        """some thing"""
    # plt.figure()
    # plt.imshow(m)
    # plt.show()