带c选项指定的颜色标签和图例的matplotlib散点图

Question

我想做this kind of scatter plot点的颜色由“c”选项指定，图例显示颜色的含义。

我的数据来源如下：

scatter_x = [1,2,3,4,5]
scatter_y = [5,4,3,2,1]
group = [1,3,2,1,3] # each (x,y) belongs to the group 1, 2, or 3.

我试过这个：

plt.scatter(scatter_x, scatter_y, c=group, label=group)
plt.legend()

不幸的是，我没有像预期的那样得到传说。如何正确展现传奇？我希望有五行，每行显示颜色和组对应关系。

Answer 1

如您提到的示例所示，为每个组调用plt.scatter：

import numpy as np
from matplotlib import pyplot as plt

scatter_x = np.array([1,2,3,4,5])
scatter_y = np.array([5,4,3,2,1])
group = np.array([1,3,2,1,3])
cdict = {1: 'red', 2: 'blue', 3: 'green'}

fig, ax = plt.subplots()
for g in np.unique(group):
    ix = np.where(group == g)
    ax.scatter(scatter_x[ix], scatter_y[ix], c = cdict[g], label = g, s = 100)
ax.legend()
plt.show()

Answer 2

看看这个：

import matplotlib.pyplot as plt
import numpy as  np

fig, ax = plt.subplots()
scatter_x = np.array([1,2,3,4,5])
scatter_y = np.array([5,4,3,2,1])
group = np.array([1,3,2,1,3])
for g in np.unique(group):
    i = np.where(group == g)
    ax.scatter(scatter_x[i], scatter_y[i], label=g)
ax.legend()
plt.show()