List reference at offset

[Colin.Hankins at touit.com]

On May 27, 11:19 am, Peter Otten <__pete... at web.de> wrote:
> Colin.Hank... at touit.com wrote:
> > Disclaimer: I'm learning python and would like to use it in a
> > project.
>
> > The project will have many large matricies. In one particular instance
> > I need to reference a smaller submatrix of the larger matrix. I don't
> > want to create a new copy or even change any of the values, I just
> > want to quickly and easily be able to look at this sub matrix.
>
> > So I am using lists of lists for the matricies (I am also playing with
> > NumPy) and is there anyway to create a pointer to an offset in a
> > list?
>
> > I know you can have A = B = [] which would be the same.
>
> > And I know I can simply do a B[x + offset to submatrix].
>
> > But I was hoping there may be a way to just have a pointer? Or is
> > there another more efficient method to do this in python?
>
> What you describe is what numpy does:
>
> """
> Therefore, a regular indexing expression on an ndarray can always produce an
> ndarray object without copying any data. This is sometimes referred to as
> the “view” feature of array indexing, and one can see that it is enabled by
> the use of striding information in the underlying ndarray object. The
> greatest benefit of this feature is that it allows indexing to be done
> very rapidly and without exploding memory usage (because no copies of the
> data are made).
> """- Hide quoted text -
>
> - Show quoted text -

Thank you. That certainly did the trick!