numpy.count_nonzero¶
-
numpy.
count_nonzero
(a, axis=None)[source]¶ Counts the number of non-zero values in the array
a
.The word “non-zero” is in reference to the Python 2.x built-in method
__nonzero__()
(renamed__bool__()
in Python 3.x) of Python objects that tests an object’s “truthfulness”. For example, any number is considered truthful if it is nonzero, whereas any string is considered truthful if it is not the empty string. Thus, this function (recursively) counts how many elements ina
(and in sub-arrays thereof) have their__nonzero__()
or__bool__()
method evaluated toTrue
.Parameters: a : array_like
The array for which to count non-zeros.
axis : int or tuple, optional
Axis or tuple of axes along which to count non-zeros. Default is None, meaning that non-zeros will be counted along a flattened version of
a
.New in version 1.12.0.
Returns: count : int or array of int
Number of non-zero values in the array along a given axis. Otherwise, the total number of non-zero values in the array is returned.
See also
nonzero
- Return the coordinates of all the non-zero values.
Examples
>>> np.count_nonzero(np.eye(4)) 4 >>> np.count_nonzero([[0,1,7,0,0],[3,0,0,2,19]]) 5 >>> np.count_nonzero([[0,1,7,0,0],[3,0,0,2,19]], axis=0) array([1, 1, 1, 1, 1]) >>> np.count_nonzero([[0,1,7,0,0],[3,0,0,2,19]], axis=1) array([2, 3])