Function PyArray_CountNonzero

numpy/core/src/multiarray/item_selection.c:2646–2762

NUMPY_API * Counts the number of non-zero elements in the array. * * Returns -1 on error. */

 * Returns -1 on error.
 */
NPY_NO_EXPORT npy_intp
PyArray_CountNonzero(PyArrayObject *self)
{
    PyArray_NonzeroFunc *nonzero;
    char *data;
    npy_intp stride, count;
    npy_intp nonzero_count = 0;
    int needs_api = 0;
    PyArray_Descr *dtype;

    NpyIter *iter;
    NpyIter_IterNextFunc *iternext;
    char **dataptr;
    npy_intp *strideptr, *innersizeptr;
    NPY_BEGIN_THREADS_DEF;

    dtype = PyArray_DESCR(self);
    /* Special low-overhead version specific to the boolean/int types */
    if (PyArray_ISALIGNED(self) && (
            PyDataType_ISBOOL(dtype) || PyDataType_ISINTEGER(dtype))) {
        return count_nonzero_int(
            PyArray_NDIM(self), PyArray_BYTES(self), PyArray_DIMS(self),
            PyArray_STRIDES(self), dtype->elsize
        );
    }

    nonzero = PyArray_DESCR(self)->f->nonzero;
    /* If it's a trivial one-dimensional loop, don't use an iterator */
    if (PyArray_TRIVIALLY_ITERABLE(self)) {
        needs_api = PyDataType_FLAGCHK(dtype, NPY_NEEDS_PYAPI);
        PyArray_PREPARE_TRIVIAL_ITERATION(self, count, data, stride);

        if (needs_api){
            while (count--) {
                if (nonzero(data, self)) {
                    ++nonzero_count;
                }
                if (PyErr_Occurred()) {
                    return -1;
                }
                data += stride;
            }
        }
        else {
            NPY_BEGIN_THREADS_THRESHOLDED(count);
            while (count--) {
                if (nonzero(data, self)) {
                    ++nonzero_count;
                }
                data += stride;
            }
            NPY_END_THREADS;
        }

        return nonzero_count;
    }

    /*