[Numpy-discussion] New behavior of allclose

Charles R Harris charlesr.harris at gmail.com
Thu Nov 5 17:15:26 EST 2015

On Thu, Nov 5, 2015 at 2:50 PM, Ralf Gommers <ralf.gommers at gmail.com> wrote:

> On Wed, Nov 4, 2015 at 8:28 PM, Charles R Harris <
> charlesr.harris at gmail.com> wrote:
>> Hi All,
>> This is to open a discussion of a change of behavior of `np.allclose`.
>> That function uses `isclose` in numpy 1.10 with the result that array
>> subtypes are preserved whereas before they were not. In particular, memmaps
>> are returned when at least one of the inputs is a memmap. By and large I
>> think this is a good thing, OTOH, it is a change in behavior. It is easy to
>> fix, just run `np.array(result, copy=False)` on the current `result`, but I
>> thought I'd raise the topic on the list in case there is a good argument to
>> change things.
> Why would it be good to return a memmap? And am I confused or does your
> just merged PR [1] revert the behavior you say here is a good thing?

Good thing for isclose, not allclose. I was thinking of very large files
that might exceed memory in the isclose case, but an argument could be made
for other subtypes. Allclose, OTOH, always returns a scalar.

I went ahead with boolean for allclose because 1) it is backward
compatible, 2) Nathaniel tended in that direction, 3) the conversation here
is tending in that direction, 4) I tend in that direction, and finally, I
want to get 1.10.2rc1 out this weekend ;)

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