[SciPy-User] Quick "grid" creation

[Chris Weisiger]

You could use arange and then blow the array up using some scaling
function, maybe? Google suggests the Kronecker product:
http://stackoverflow.com/questions/7525214/how-to-scale-a-numpy-array
http://docs.scipy.org/doc/numpy/reference/generated/numpy.kron.html

a = numpy.arange(20*20).reshape(20, 20)
b = numpy.kron(a, numpy.ones((100, 100))

-Chris


On Fri, Aug 2, 2013 at 11:54 AM, Jose Gomez-Dans <jgomezdans at gmail.com>wrote:

> Hi,
> I'd like to quickly create a labelled grid to overlay on an array and use
> as labels (eg scipy.ndimage.sum takes a labels option to calculate
> statistics using a different array as a mask. My attempts to quickly
> produce said masks work, but are a bit embarrassing...
>
> *a = np.zeros((100, 100), dtype=np.int)*
> *cnt = 0*
> *for i in xrange(20):                    *
> *    for j in xrange(20):*
> *        cnt += 1*
> *        a[(i*5):((i+1)*5), (j*5):((j+1)*5)] = cnt*
>
> So the above works, but it quickly gets cumbersome with large arrays, and
> arrays where the ratio between how many cells in the finer array to the
> coarser array. Is there some "keys in hand" solution for this problem?
>
> Thanks!
> Jose
>
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