Function PyArray_Squeeze

numpy/core/src/multiarray/shape.c:530–576

NUMPY_API * * return a new view of the array object with all of its unit-length * dimensions squeezed out if needed, otherwise * return the same array. */

 * return the same array.
 */
NPY_NO_EXPORT PyObject *
PyArray_Squeeze(PyArrayObject *self)
{
    PyArrayObject *ret;
    npy_bool unit_dims[NPY_MAXDIMS];
    int idim, ndim, any_ones;
    npy_intp *shape;

    ndim = PyArray_NDIM(self);
    shape = PyArray_SHAPE(self);

    any_ones = 0;
    for (idim = 0; idim < ndim; ++idim) {
        if (shape[idim] == 1) {
            unit_dims[idim] = 1;
            any_ones = 1;
        }
        else {
            unit_dims[idim] = 0;
        }
    }

    /* If there were no ones to squeeze out, return the same array */
    if (!any_ones) {
        Py_INCREF(self);
        return (PyObject *)self;
    }

    ret = (PyArrayObject *)PyArray_View(self, NULL, &PyArray_Type);
    if (ret == NULL) {
        return NULL;
    }

    PyArray_RemoveAxesInPlace(ret, unit_dims);

    /*
     * If self isn't not a base class ndarray, call its
     * __array_wrap__ method
     */
    if (Py_TYPE(self) != &PyArray_Type) {
        PyArrayObject *tmp = PyArray_SubclassWrap(self, ret);
        Py_DECREF(ret);
        ret = tmp;
    }

    return (PyObject *)ret;
}

/*
 * Just like PyArray_Squeeze, but allows the caller to select