numpy create 2D mask from list of indices [+ then draw from masked array]

Question

I have a 2-D array of values and need to mask certain elements of that array (with indices taken from a list of ~ 100k tuple-pairs) before drawing random samples from the re

Answer 1

You can do it efficently using sparse coo matrix

from scipy import sparse
xys=[(1,2),(3,4),(6,9),(7,3)]

coords = zip(*xys)
mask = sparse.coo_matrix((numpy.ones(len(coords[0])), coords ), shape= master_array.shape, dtype=bool)
draws=numpy.random.choice( master_array[~mask.toarray()].flatten(), size=10)