# test alpha blending when both alpha and array alpha are passed
import matplotlib.pyplot as plt
from matplotlib.colors import ListedColormap
import numpy as np
fig, axs = plt.subplots(3, 4, figsize=(12, 10), layout='compressed')
for ax in axs.flat:
 ax.set(facecolor='red', xticks=[], yticks=[])
mapped = np.array([
 [0.1, 1.0],
 [1.0, 0.1]
])
rgb = np.repeat(mapped[:, :, np.newaxis], 3, axis=2)
rgba = np.concatenate(
 [
 rgb,
 [
 [[1.0], [0.9]],
 [[0.8], [0.7]],
 ]
 ],
 axis=2
)
alpha_scalar = 0.5
alpha_2d = np.full_like(mapped, alpha_scalar)
cmap_with_alpha = ListedColormap(
 np.concatenate([plt.cm.viridis.colors,
 np.full((len(plt.cm.viridis.colors), 1), alpha_scalar)],
 axis=1),
)
# axs[0,0].imshow(rgb, alpha=alpha_scalar)
# axs[0,1].imshow(rgb, alpha=alpha_2d)
for ax, alpha, t in zip(axs, [None, alpha_scalar, alpha_2d], ['off', 'float', 'array']):
 ax[0].imshow(mapped, alpha=alpha)
 ax[0].set_title(f'2D, alpha={alpha_scalar} {t}')
 ax[1].imshow(mapped, cmap=cmap_with_alpha, alpha=alpha)
 ax[1].set_title(f'2D with {alpha_scalar} alpha cmap, alpha={alpha_scalar} {t}')
 ax[2].imshow(rgb, alpha=alpha)
 ax[2].set_title(f'RGB, alpha={alpha_scalar} {t}')
 ax[3].imshow(rgba, alpha=alpha)
 ax[3].set_title(f'RGBA, alpha={alpha_scalar} {t}')
plt.show()