Method reduce

numpy/ma/core.py:6956–6987

Reduce target along the given axis.

(self, target, axis=np._NoValue)

        return where(self.compare(a, b), a, b)

    def reduce(self, target, axis=np._NoValue):
        "Reduce target along the given axis."
        target = narray(target, copy=None, subok=True)
        m = getmask(target)

        if axis is np._NoValue and target.ndim > 1:
            name = self.__name__
            # 2017-05-06, Numpy 1.13.0: warn on axis default
            warnings.warn(
                f"In the future the default for ma.{name}.reduce will be axis=0, "
                f"not the current None, to match np.{name}.reduce. "
                "Explicitly pass 0 or None to silence this warning.",
                MaskedArrayFutureWarning, stacklevel=2)
            axis = None

        if axis is not np._NoValue:
            kwargs = {'axis': axis}
        else:
            kwargs = {}

        if m is nomask:
            t = self.f.reduce(target, **kwargs)
        else:
            target = target.filled(
                self.fill_value_func(target)).view(type(target))
            t = self.f.reduce(target, **kwargs)
            m = umath.logical_and.reduce(m, **kwargs)
            if hasattr(t, '_mask'):
                t._mask = m
            elif m:
                t = masked
        return t

    def outer(self, a, b):
        "Return the function applied to the outer product of a and b."