Checkerboard in Numpy

Here's a question on SO about how to make a checkerboard in Numpy (like you see on pdfs when as "the classic representation for "no pixels", or transparent." I have no doubt that I had the correct answer, but I could not buy a vote. Even from a guy with 22.9 K rep. Sheesh.

We use hstack and vstack to stack "unit" squares of solid color:

>>> import numpy as np >>> u = 15 >>> b = np.zeros(u**2) >>> b.shape = (u,u) >>> w = b + 0x99 >>> >>> width = 20 # squares across of a single type >>> row1 = np.hstack([w,b]*width) >>> row2 = np.hstack([b,w]*width) >>> board = np.vstack([row1,row2]*width) >>> board.shape (600, 600)

Now just slice it down to what's needed

>>> width_actual = 357 >>> height_actual = 239 >>> board = board[:height_actual,:width_actual] >>> board.shape (239, 357)