montage2d

montage2d.py

import numpy as np
from scipy import misc
import pylab as pl
from skimage.util import shape

def foo(p):
    alpha = int(np.ceil(np.sqrt(p.shape[0])))

    # -- fill missing squares
    cst = p.mean()
    n_missing = int((alpha**2.) - p.shape[0])
    missing = np.ones((n_missing,) + p.shape[1:]) * cst
    b = np.vstack((p, missing))

    # -- reshape to 2d montage
    c = b.reshape(alpha, alpha, b.shape[1], b.shape[2])
    d = c.swapaxes(1, 2)
    e = d.reshape(d.shape[0] * d.shape[1], d.shape[2] * d.shape[3])

    return e

def main():
    psize = (7, 7)
    n_patches = 15

    l = misc.lena() / 255.
    p = shape.view_as_windows(l, psize)
    p = p.reshape((-1,) + psize)
    ridx = np.random.permutation(p.shape[0])
    p = p[ridx]
    p = p[:n_patches]

    e = foo(p)
    pl.matshow(e, cmap=pl.cm.gray)
    pl.show()

if __name__ == '__main__':
    main()