from matplotlib import pyplot as plt
from matplotlib.colors import ListedColormap
import numpy as np
plt.rcParams["figure.figsize"] = [7.50，3.50]
plt.rcParams["figure.autolayout"] = True
data = np.random.rand(5, 5)
cmap = ListedColormap(['r', 'g', 'b'])
plt.imshow(data, cmap=cmap)
plt.show()