multiply numpy ndarray with 1d array along a given axis

Question

It seems I am getting lost in something potentially silly. I have an n-dimensional numpy array, and I want to multiply it with a vector (1d array) along some dimension (whi

Answer 1

You could build a slice object, and select the desired dimension in that:

import numpy as np

a = np.arange(18).reshape((3,2,3))
b = np.array([1,3])

ss = [None for i in range(a.ndim)]
ss[1] = slice(None)    # set the dimension along which to broadcast

print ss  #  [None, slice(None, None, None), None]

c = a*b[ss]