[Numpy-discussion] Inconsistency with __index__() for rank-1 arrays?
Pauli Virtanen
pav@iki...
Fri Oct 29 05:59:04 CDT 2010
pe, 2010-10-29 kello 12:48 +0200, Francesc Alted kirjoitti:
> A Friday 29 October 2010 12:18:20 Pauli Virtanen escrigué:
> > Fri, 29 Oct 2010 09:54:23 +0200, Francesc Alted wrote:
> > [clip]
> >
> > > My vote is +1 for deprecating ``array([scalar])`` as a scalar index
> > > for NumPy 2.0.
> >
> > I'd be -0 on this, since 1-element Numpy arrays function like scalars
> > in several other contexts, e.g. in casting to Python types and in
> > boolean context.
> >
> > Note also that at least Python's struct module (mis-?)uses
> > __index__() for casting inputs to integers.
>
> Uh, could you put some examples of this please?
Sure:
if array([[1]]):
print "OK"
x = float(array([[1]]))
and for the second point, in Python/Modules/_struct.c:
95 static PyObject *
96 get_pylong(PyObject *v)
97 {
98 assert(v != NULL);
99 if (!PyLong_Check(v)) {
100 /* Not an integer; try to use __index__ to convert. */
101 if (PyIndex_Check(v)) {
>>> import numpy as np, struct
>>> struct.pack("i", np.array([1]))
'\x01\x00\x00\x00'
--
Pauli Virtanen
More information about the NumPy-Discussion
mailing list