[Numpy-discussion] Offset 2D arrays
Eric Nodwell
nodwell at physics.ubc.ca
Mon Sep 17 16:35:03 CDT 2001
Mike,
As was pointed out to me when I had a similar query, one way to do
this is to define a class which inherits UserArray and refine indexing
and slicing. I actually shifted by an offset of one in the opposite
direction to what you seem to require. I had intended to generalize
to arbitrary offsets, but haven't had the time yet. Anyway, you're
welcome to grab my code at
http://www.physics.ubc.ca/~mbelab/python/arrayone as a starting point
for your class. There are still some issues and quirkiness with the
code, but they're documented along with work-arounds, and suggestions
for fixes have been made on this mailing list. Again, it's a matter
of time...
regards,
Eric
On Mon, Sep 17, 2001 at 05:20:06PM -0600, Mike Romberg wrote:
>
> I am attempting to create 2D arrays which are offset copies of a
> given starting array. For example if I have a 2D array like this:
>
> array([[1, 2, 3],
> [4, 5, 6],
> [7, 8, 9]])
>
> I would like to offset it by some amount in either or both the x and
> y dimension. Lets say that both the x and y offset would be 1. Then
> I would like to have an array like this:
>
>
>
> array([[5, 6, 0],
> [8, 9, 0],
> [0, 0, 0]])
>
> Here I don't really care about the values which are now zero. The
> main point is that now I can compare the data values at any given
> (x,y) point with the values at the adjacent point (over one on each
> axis). This would be useful for the kinds of calculations we need to
> do. I just can't come up with a numeric way to do this. Does anyone
> have any ideas?
>
> Thanks alot,
>
> Mike Romberg (romberg at fsl.noaa.gov)
>
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--
********************************
Eric Nodwell
Ph.D. candidate
Department of Physics
University of British Columbia
tel: 604-822-5425
fax: 604-822-5324
nodwell at physics.ubc.ca
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