python - 在 Matplotlib 中填充 3 个图形之间的空间

Question

我需要填写图表之间的阴影区域。我应该在 fill_between 中写什么来做到这一点？

import numpy as np
import matplotlib.pyplot as plt

y = lambda z: (2 * z - z ** 2) ** (1 / 2)
y1 = lambda x: (6 * x - x ** 2) ** (1 / 2)
y2 = lambda c: c
x = np.linspace(0, 12, 500)
z = np.linspace(0, 12, 500)
c = np.linspace(0, 12, 500)
plt.ylim(0, 4)
plt.xlim(0, 4)

plt.plot(z, y(z), color='blue', label="$y=\\sqrt{2x-x^2}$")
plt.plot(c, y2(c), color='black', label='$y=x$')
plt.plot(x, y1(x), color='red', label='$y=\\sqrt{6x-x^2}$')
plt.plot([0, 4], [0, 0], color='yellow', label='y=0')
plt.grid(True, zorder=5)
miny = np.minimum(y2(c), y1(x))
plt.fill_between(x, y(z), miny, where=(miny > y(x)), alpha=0.5)
plt.legend()
plt.show()

标签： pythonnumpymatplotlibmathplot

Answer 1

使您的函数的域相同（例如[0, 4]）。下面的代码做你想要的：

import numpy as np
import matplotlib.pyplot as plt

x =  np.linspace(0, 4, 500)

y = np.piecewise(x, [x <= 2, x > 2], [lambda x: np.sqrt(2 * x - x ** 2), 0])
y1 = np.sqrt(6 * x - x ** 2)
y2 = x
y3 = 0*x


plt.plot(x, y, color='blue', label="$y=\\sqrt{2x-x^2}$")
plt.plot(x, y1, color='red', label='$y1=\\sqrt{6x-x^2}$')
plt.plot(x, y2, color='black', label='$y2=x$')
plt.plot(x, y3, color='yellow', label='y3=0')
plt.grid(True, zorder=5)
miny = np.minimum(y2, y1)
plt.fill_between(x, y, miny, where = (miny > y), alpha=0.5)
plt.legend()
plt.show()