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Getting the number of non-zero elements in a NumPy array

schedule Aug 12, 2023
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To get the number of non-zero elements in a NumPy array use the count_nonzero(~) method.

Examples

1D array

To count the number of non-zero elements in a 1D array:

np.count_nonzero([1,0,2,0,3])
3

2D array

To count the number of non-zero elements in a 2D array:

np.count_nonzero([[1,0,1],[0,1,0]])
3

To count the number of non-zero elements row-wise:

np.count_nonzero([[1,0,1],[0,1,0]], axis=1)
array([2, 1])

To count the number of non-zero elements column-wise:

np.count_nonzero([[1,0,1],[0,1,0]], axis=0)
array([1, 1, 1])
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Published by Arthur Yanagisawa
Edited by 0 others
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