random_patches.py

w = 96
n = 20000
l = 32

def rand_ranges(a, b, l, size):
    r  = np.repeat(np.arange(l, dtype=np.intp)[np.newaxis], size, axis=0)
    r += np.random.randint(a, b-l, size=size)[:,np.newaxis]
    return r

si0 = np.random.randint(0, images.shape[0], size=n)
si1 = rand_ranges(0, w, l, size=n);
si2 = rand_ranges(0, w, l, size=n);

i5 = (
    si0.reshape(n, 1, 1),
    si1.reshape(n, l, 1),
    si2.reshape(n, 1, l)
)

patches = zca_images[i5]