Re: drop array elements

[Craig Markwardt <craigmnet(at)cow.physics.wisc.edu>]

Matthew Kay <mwk@crml.uab.edu> writes:
> Hi,
> 
> Would anyone have any suggestions for an easy way
> to drop elements in an array? For example, say 'a'
> is a 14x1024 array and 'b' is a 1x25 array of row
> indicies  in 'a' that should be dropped. Is there
> a simple command for re-assigning 'a', without the
> 25 rows indicated in 'b'?

The best way to go after this is to rephrase the question so that BP
(b-primed) is the list of rows to *keep*.  Then it's easy:

  a = a(*,bp)

This, in the end, is what JD was getting after.  A way to see this
more clearly might be to do it in steps like this:

tmp = intarr(1024) + 1       ;; Create a mask with all 1's by default
tmp(b) = 0                   ;; Zero out the discarded rows
bp = where(tmp EQ 1, ct)     ;; Find the kept rows - compute BP
if ct GT 0 then a = a(*,bp)  ;; Extract those rows

Good luck,
Craig

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Craig B. Markwardt, Ph.D.         EMAIL:    craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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