[SciPy-user] problem referencing single element arrays

Alan Jackson alan@ajackson....
Wed Apr 30 22:03:41 CDT 2008


On Wed, 30 Apr 2008 21:39:53 -0500
"Robert Kern" <robert.kern@gmail.com> wrote:

> On Wed, Apr 30, 2008 at 9:11 PM, Alan Jackson <alan@ajackson.org> wrote:
> > Having a problem with numpy that has me stumped.
> >
> >  I have a large set of arrays. I want to set up cross reference lists of
> >  elements within those arrays, with the lists just being pointers to the objects
> >  (floating point numbers) stored in the arrays.
> >
> >  The problem is that some arrays have only a single element, so when I try to
> >  store a[0] for a single element array, I get an error, "0-d arrays can't be
> >  indexed". How do I get a pointer to the object stored and not the array for
> >  single element arrays?
> 
> a[()]
> 
> >  Or maybe I don't want to be doing this?
> 
> Quite possibly. Can you expand on your use case?
> 

Imagine a 3D coordinate system. I have connected, non-recumbent sheets
of various sizes in this 3D space. I set up a dictionary of arrays where
a set of 3 arrays contains the X, Y, Z-values of the points on a sheet, 
the dictionary so I can name each sheet.

I'd also like to access the data points vertically, at a particular X,Y
what are all the sheets and points? That's the purpose of my cross reference.

It's actually a bit more complicated than this - I have multiple attributes
attached to each point on each sheet, as well as sheet-level attributes.

I did this in perl a few years ago - I think it will be much better with
numpy.

I like that bit of magic you showed.

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