python - How to remove the adjacent duplicate value in a numpy array?

Question

Given a numpy array, I wish to remove the adjacent duplicate non-zero value and all the zero value. For instance, for an array like that: [0,0,1,1,1,2,2,0,1,3,3,3], I'd like to transform it to: [1,2,1,3]. Do you know how to do it? I just know np.unique(arr) but it would remove all the duplicate value and keep the zero value. Thank you in advance!

Answer 1

You can use the groupby method from itertools combined with list comprehension for this problem:

from itertools import groupby
[k for k,g in groupby(a) if k!=0]

# [1,2,1,3]

Data:

a = [0,0,1,1,1,2,2,0,1,3,3,3]