[Numpy-discussion] nonzero() behaviour has changed

[Ed Schofield]

Bill Baxter wrote:
> On 5/18/06, *Ed Schofield* <schofield at ftw.at
> <mailto:schofield at ftw.at>> wrote:
>
>     Bill Baxter wrote:
>     > Sure would be nice if all you had to type was a.nonzero().T,
>     though... ;-P
>
>     No, this wouldn't be possible -- the output of the nonzero method is a
>     tuple, not an array.  Perhaps this is why it's not _that_ obvious ;) 
>
>
> Oh, I see.  I did miss that bit.  I think I may have even done
> something recently myself like
>    vstack(where(a > val)).transpose()
> not realizing that plain old transpose() would work in place of
> vstack(xxx).transpose().
>
> If you feel like copy-pasting your doc addition for nonzero() over to
> where() also, that would be nice. 

Okay, done.

> What other functions work like that?   ... <me rummages around a
> little> ... actually it looks like most other functions similar to
> nonzero() return a boolean array, then you use where() if you need an
> index list.  isnan(), iscomplex(), isinf(), isreal(), isneginf(), etc
> and of course all the boolean operators like a>0.   So nonzero() is
> kind of an oddball.  Is it actually any different from where(a!=0)?

I think it's equivalent, only slightly more efficient...


-- Ed