d2.append([])
for y in range(30):
    d1[-1].append(y + x)
for y in range(37):
    d2[-1].append(y + x)
fig, axes = plt.subplots(ncols=4, figsize=(10, 4))
axes[0].pcolormesh(np.array(d1), cmap=plt.cm.coolwarm)
axes[1].pcolormesh(np.array(d2), cmap=plt.cm.coolwarm)
axes[2].pcolormesh(np.array(d2), cmap=plt.cm.coolwarm)
axes[2].set_ylim(bottom=0, top=d2.shape[0])
axes[2].set_xlim(left=0, right=d2.shape[1])
axes[2].axis('tight')
axes[3].imshow(np.array(d2), cmap=plt.cm.coolwarm)
pcolormesh добавляет пустые белые столбцы