matplotlib（1）-- figure创建

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-3, 3, 50)
y1 = 2 * x + 1
y2 = x ** 2

#figure 1
plt.figure()
plt.plot(x, y1)

#figure 2
plt.figure()
plt.plot(x, y2)

#figure 4，指定figure的编号并指定figure的大小
plt.figure(num = 4, figsize = (8, 5))
plt.plot(x, y1, color = "red", linewidth = 5.0, linestyle = '--')    #指定线的颜色, 宽度和类型
plt.plot(x, y2)

plt.show()