python - 对三角形区域进行着色

Question

这是我的代码：

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

x = np.random.randint(1,100,100)
y = np.random.randint(-500,200,100)
plt.scatter(x, y)
ax = plt.gca()
ax.invert_yaxis()


x1, y1 = [0, 100], [-200, 0]
x2, y2 = [0, 0], [0, -200]
x3, y3 = [0, 100], [0, 0]

plt.plot(x1,y1,x2,y2,x3,y3, marker = 'o')
plt.show()

plt.show()

有两个问题

1. 我希望三角形手臂的颜色相同，我该怎么做？
2. 我想对三角形下方的区域进行阴影处理，使其半透明，即我可以看到三角形内部散点图的点。那可行吗？

标签： pythonmatplotlibplotscatter-plot

Answer 1

更一般地说，您可以使用 matplotlib 补丁和集合（示例）填充任何多边形：

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection    

x = np.random.randint(1,100,100)
y = np.random.randint(-500,200,100)
plt.scatter(x, y)
ax = plt.gca()
ax.invert_yaxis()


vertices = np.array([[0,0],[0,-200.0],[100.0,0]])

patches = []
triangle = Polygon(vertices, True)
patches.append(triangle)

p = PatchCollection(patches, alpha=0.4)
ax=plt.gca()
ax.add_collection(p)

plt.show()