Python, numpy, values of dicts, and numpy.where

Question

if I have a numpy.array value that is a dict, say, { 'this' : 'that' }, how can I use numpy.where() to return array coordinates for values that are a dict?  Or even better, dicts with an index of 'this' in them?  I'd much prefer to do this without a loop (at that would be very slow).  Thanks!

Answer 1

One way to do this without a loop:
def myfunc(x):
return type(x) == dict and 'this' in x
myfuncv = numpy.frompyfunc(myfunc, 1, 1)
indices = numpy.where(myfuncv(some_array))
However, you're not likely to see a significant speed improvement over calling myfunc in a loop, since either way, you're still calling a Python function for every element of the array. Unfortunately, I don't see any way around this, since determining the type of an object and testing for a key in a dict are fundamentally Python operations. If you disagree, perhaps you should clarify your problem a bit and give some more context.