Indices of fixed size sub-matrices of numpy array

Question

I am implementing an algorithm which requires me to look at non-overlapping consecutive submatrices within a (strictly two dimensional) numpy array. eg, for the 12 by 12

Answer 1

I'm adding this answer to an old question since an edit has bumped this question up. Here's an alternative way to calculate blocks:

size = 3
lenr, lenc = int(a.shape[0]/size), int(a.shape[1]/size)

t = a.reshape(lenr,size,lenc,size).transpose(0, 2, 1, 3)

Profiling shows that this is the fastest. Profiling done with python 3.5, and the results from map passed to array() for compatibility, since in 3.5 map returns an iterator.

reshape/transpose:   643 ns per loop
reshape/index:       45.8 µs per loop
Map/split:           10.3 µs per loop

It's interesting that the iterator version of map is faster. In any case, using reshape and transpose is fastest.