Question

I need to get the first and last dimension of an numpy.ndarray of arbitrary size.

If I have shape(A) = (3,4,4,4,4,4,4,3)
my first Idea would be to do result = shape(A)[0,-1] but that doesn’t seem to work with tuples, why not ??

Is there a neater way of doing this than

s=shape(A)
result=(s[0], s[-1])

Thanks for any help

Answer 1

I don’t know what’s wrong about

(s[0], s[-1])

A different option is to use operator.itemgetter():

from operator import itemgetter
itemgetter(0, -1)(s)

I don’t think this is any better, though. (It might be slightly faster if you don’t count the time needed to instantiate the itemgetter instance, which can be reused if this operation is needed often.)