from matplotlib import pyplot as plt
from mpl_toolkits.axes_grid1.anchored_artists import AnchoredSizeBar
import numpy as np

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

data = np.random.rand(5, 5)

img = plt.imshow(data, cmap="YlGnBu")
ax = plt.gca()
scalebar = AnchoredSizeBar(ax.transData, 1, "1米", 9)

ax.add_artist(scalebar)
ax.axis('off')
plt.show()