Test if a numpy array is a member of a list of numpy arrays, and remove it from the list

Question

When testing if a numpy array c is member of a list of numpy arrays CNTS:

import numpy as np

c = np.array([[[ 75, 763]],
                  


        

Answer 1

This solution could work for this case:

def arrayisin(array, list_of_arrays):
    for a in list_of_arrays:
        if np.array_equal(array, a):
            return True
    return False

This function iterates over a list of arrays and tests the equality against some other array. So the usage would be:

>>> arrayisin(c, CNTS)
True

To remove the array from the list, you can get the index of the array and then use list.pop. In the function get_index, we enumerate the list of arrays, meaning we zip the indices of the list and the contents of the list. If there is a match, we return the index of the match.

def get_index(array, list_of_arrays):
    for j, a in enumerate(list_of_arrays):
        if np.array_equal(array, a):
            return j
    return None

idx = get_index(c, CNTS)  # 1
CNTS.pop(idx)

Please see the python data structures tutorial for the documentation of list.pop https://docs.python.org/3/tutorial/datastructures.html