Multiply two arrays with different dimensions using numpy

Question

I need a faster/optimised version of my current code:

import numpy as np

a = np.array((1, 2, 3))
b = np.array((10, 20, 30, 40, 50, 60, 70, 80))

print([i*b for i in a])

Is there any faster way to do this using numpy functions (maybe without reshaping and blowing up the whole thing)?

kennytm · Accepted Answer · 2013-11-21 12:30:11Z

11

Looks like the outer product.

>>> np.outer(a, b)
array([[ 10,  20,  30,  40,  50,  60,  70,  80],
       [ 20,  40,  60,  80, 100, 120, 140, 160],
       [ 30,  60,  90, 120, 150, 180, 210, 240]])

answered Nov 21, 2013 at 12:30

kennytm

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1 Comment

tamasgal Over a year ago

This is it, exactly ; )

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