CODEWITHSUNDEEP
pythonnumpy
Atihska
Atihska

Reputation: 5126

How can I map 2 numpy arrays with same indices

I am trying to map 2 numpy arrays as [x, y] similar to what zip does for lists and tuples.

I have 2 numpy arrays as follows:

arr1 = [1, 2, 3, 4]
arr2 = [5, 6, 7, 8]

I am looking for an output as np.array([[[1, 5], [2, 6], [3, 7], [4, 8]]])

I tried this but it maps every value and not with same indices. I can add more if conditions here but is there any other way to do so without adding any more if conditions.

res = [arr1, arr2] for a1 in arr1 for a2 in arr2]

Upvotes: 4

Views: 961

Answers (3)

user3483203
user3483203

Reputation: 51165

You are looking for np.dstack

Stack arrays in sequence depth wise (along third axis).

np.dstack([arr1, arr2])

array([[[1, 5],
        [2, 6],
        [3, 7],
        [4, 8]]])

Upvotes: 3

pault
pault

Reputation: 43494

IIUC, one way is to use numpy.vstack() followed by transpose():

import numpy as np
arr1 = np.array([1, 2, 3, 4])
arr2 = np.array([5, 6, 7, 8])
print(np.vstack([arr1, arr2]).transpose())
#array([[1, 5],
#       [2, 6],
#       [3, 7],
#       [4, 8]])

Or you could pass the output of zip to the array constructor:

print(np.array(zip(arr1, arr2)))
#array([[1, 5],
#       [2, 6],
#       [3, 7],
#       [4, 8]])

Upvotes: 2

Gerik
Gerik

Reputation: 736

The built in zip command is the job for you here. It'll do exactly what you're asking.

arr1 = [1,2,3,4]
arr2 = [5,6,7,8]
list(zip(arr1, arr2))
[(1, 5), (2, 6), (3, 7), (4, 8)]

https://docs.python.org/3/library/functions.html#zip

Upvotes: 0

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