[Matplotlib] plt.subplots(ax = ax.flatten) ax.flatten(): Transform n*m to 1*nm 1-D Array fig, ax = plt.subplots(nrows=2,ncols=2,sharex='all',sharey='all') ax = ax.flatten() for i in range(4): img = image[i].reshape(28, 28) ax[i].imshow(img, cmap='Greys', interpolation='nearest') # ax[i] is available Without flatten() fig, ax = plt.subplots(nrows=2,ncols=2,sharex='all',sharey='all') for i in range(4): img = image[i].reshape(28, 28) ax[0, 0].imshow(img, cmap='Greys', interpolation='nearest') ax[0, 1].imshow(img, cmap='Greys', interpolation='nearest') ax[1, 0].imshow(img, cmap='Greys', interpolation='nearest') ax[1, 1].imshow(img, cmap='Greys', interpolation='nearest') # ax[i] is unavailable 正确不？