Delete specific values in 2-Dimension array - Numpy

Question

import numpy as np

I have two arrays of size n (to simplify, I use in this example n = 2):

A = array([[1,2,3],[1,2,3]])

B has two dimensions with n time a random integer: 1, 2 or 3.

Let's pretend:

B = array([[1],[3]])

What is the most pythonic way to subtract B from A in order to obtain C, C = array([2,3],[1,2]) ?

I tried to use np.subtract but due to the broadcasting rules I do not obtain C. I do not want to use mask or indices but element's values. I also tried to use np.delete, np.where without success. Thank you.

In my case, there is no duplicate. But if there is let 's say substract the first iteration. — Theo
– Theo, Commented Sep 14, 2018 at 13:35
Check this link, hope it will help you out stackoverflow.com/questions/42557558/… — JON
– JON, Commented Sep 14, 2018 at 13:36
And what if no match is found? For ex. : B = array([[5],[3]])? — Divakar
– Divakar, Commented Sep 14, 2018 at 13:38

msi_gerva · Accepted Answer · 2018-09-14 13:39:58Z

1

This might work and should be quite Pythonic:

dd=[[val for val in A[i] if val not in B[i]] for i in xrange(len(A))]

answered Sep 14, 2018 at 13:39

msi_gerva

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2 Comments

Theo Over a year ago

Thank you. It does work with 'range' instead of 'xrange'.

msi_gerva Over a year ago

I am still using Python2.X, therefore xrange... Glad it worked!

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