CODEWITHSUNDEEP
pythonnumpy
shelper
shelper

Reputation: 10573

how to broadcast certain processing in numpy arrays

Let's say I have an numpy array

import numpy as  np
a = np.array([[1,2,3],[3,4,5]])

and I defined a function to process the data, e.g, get the product of a vector:

def vp(v):
    p = 1
    for i in v:
        p = p * i
    return p

and how can I easily broadcast the function to all the vectors in a by something like the map function for the list, e.g. vp(a) will give me [6, 60]? what if a is a 3D or even 4D array, is there a good way to broadcast such customized function?

Upvotes: 0

Views: 84

Answers (1)

Back2Basics
Back2Basics

Reputation: 7806

I think the core of your question relies on creating custom functions to apply over multidimensional datasets. For that you would use numpy.apply_along_axis().

a = array([[1, 2, 3],
       [3, 4, 5]])
np.apply_along_axis(arr = a, func1d=vp, axis=1)
> array([ 6, 60])

Yes this also works with N-Dimentional datasets.

c = array([[[ 1,  2],
        [ 3,  3],
        [ 4,  5]],

       [[16, 17],
        [18, 18],
        [19, 20]]])

np.apply_along_axis(vp, axis=1, arr=c)
> array([[  12,   30],
       [5472, 6120]])

Upvotes: 1

Related Questions