问题
I'd like to make this kind of scatter plot where the points have colors specified by the "c" option and the legend shows the color's meanings.
The data source of mine is like following:
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.
I tried this:
plt.scatter(scatter_x, scatter_y, c=group, label=group)
plt.legend()
Unfortunately, I did not get the legend as expected. How to show the legend properly? I expected there are five rows and each row shows the color and group correspondences.
回答1:
As in the example you mentioned, call plt.scatter for each group:
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()
回答2:
check this out:
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()
来源：https://stackoverflow.com/questions/47006268/matplotlib-scatter-plot-with-color-label-and-legend-specified-by-c-option