[Numpy-discussion] int and float ufunc?

Pearu Peterson pearu at cens.ioc.ee
Mon Oct 7 05:43:02 CDT 2002


On Mon, 7 Oct 2002, Andrew P. Lentvorski wrote:

> On Mon, 7 Oct 2002, Travis Oliphant wrote:
> 
> > What would you have them do?  Their current definition works for returning
> > suitable arrays as integers and floats respectively, just as the Python

    ^^^^^^^^^^^^^^^

> > documentation says these two functions should.
> 
> Okay, now I'm really confused ...
> 
> >>> import Numeric
> >>> a = Numeric.array([1.5, 2.5, 3.5], Numeric.Float64)
> >>> a
> array([ 1.5,  2.5,  3.5])
> >>> int(a)
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> TypeError: Only rank-0 arrays can be converted to Python scalars.

                  ^^^^^^^^^^^^^

> I guess I'm really dense, but how does that result constitute a definition
> that "works"?

See ^^^ above. In this case, suitable arrays are rank-0 arrays. So, the
definition works (see also below).

> > It would be an easy thing to map int() to oldarray.astype(Int) and so
> > forth but is this a good policy.  I submit it is not.
> 
> I could be persuaded either way.  I was simply wondering what the
> arguments were.

According to int.__doc__, int(..) should *always* return a Python
integer. But you are asking for an integer array as a result of 
int(array(..)); and that would be a contradiction with the Python
definition for int(anyobj).

Pearu





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