[PYTHON MATRIX-SIG] Final conventions for alpha2

[Jim Hugunin]

Konrad HINSEN wrote:
> 
> > On Sun, 18 Aug 1996, Jim Hugunin wrote:
> >
> > > Carlos Fonseca wrote:
> > >
> > > > ix=argsort(a)
> > > > A=take(a,ix)
> > > > B=take(b,ix)
> > > >
> > > > This should be enough.
> > >
> > > You have a good point here, but I think that the issue is you want a
> > > different function from Konrad.  Alright, writing functions is something
> > > I can do.  What would you like it to be called?
> >
> > How do you feel about index(a,indices,axis). Alternatively, select(...)
> > would also make sense, I think. Thanks for looking into this.
> 
> Before we add functions that differ only in details, let's consider
> the APL approach to this kind of problem: concatenate the two arrays,
> sort the result, and split them again. How efficient would that
> be in Python? It mostly depends on the concatenation (which APL
> implementations treat with special care because it is extremely
> frequently used).

Concatenation is reasonably efficient.  It could be better, but I'm
holding off on any non-trivial efficiency improvements until after
release 1.0.  Right now I think a solid, stable and reasonably complete
implementation is much more important.

I don't see any good way to solve Carlos's problem using concatenation
(without including arbitrary comparision functions for sort which I
don't want to do).  How would you reccommend he gets the equivalent of:

ix=argsort(a)
A=take(a,ix)
B=take(b,ix)

for > 1d arrays without some take-like function?

-Jim

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