'Return indices of minimum elements along an axis.
Implicit zero elements are also taken into account. If there are
several minimum values, the index of the first occurrence is returned.
Parameters
axis : {-2, -1, 0, 1, None}, optional
Axis along which the argmin is computed. If None (default), index
of the minimum element in the flatten data is returned.
out : None, optional
This argument is in the signature *solely* for NumPy
compatibility reasons. Do not pass in anything except for
the default value, as this argument is not used.
Returns
ind : np.matrix or int
Indices of minimum elements. If matrix, its size along `axis` is 1.'

def argmin(self, axis=None, out=None):

    return self._arg_min_or_max(axis, out, np.argmin, np.less)
