numpy.count_nonzero¶

numpy.
count_nonzero
(a, axis=None, *, keepdims=False)[source]¶ Counts the number of nonzero values in the array
a
.The word “nonzero” is in reference to the Python 2.x builtin 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 subarrays thereof) have their__nonzero__()
or__bool__()
method evaluated toTrue
. Parameters
 aarray_like
The array for which to count nonzeros.
 axisint or tuple, optional
Axis or tuple of axes along which to count nonzeros. Default is None, meaning that nonzeros will be counted along a flattened version of
a
.New in version 1.12.0.
 keepdimsbool, optional
If this is set to True, the axes that are counted are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input array.
New in version 1.19.0.
 Returns
 countint or array of int
Number of nonzero values in the array along a given axis. Otherwise, the total number of nonzero values in the array is returned.
See also
nonzero
Return the coordinates of all the nonzero values.
Examples
>>> np.count_nonzero(np.eye(4)) 4 >>> a = np.array([[0, 1, 7, 0], ... [3, 0, 2, 19]]) >>> np.count_nonzero(a) 5 >>> np.count_nonzero(a, axis=0) array([1, 1, 2, 1]) >>> np.count_nonzero(a, axis=1) array([2, 3]) >>> np.count_nonzero(a, axis=1, keepdims=True) array([[2], [3]])