Re: Variable stride in array indices and other enhancements

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

Jack Saba <jack@icesat1.gsfc.nasa.gov> writes:
> 
> Given the post by Richard French noting that IDL 5.3 is due out in
> October, 
> maybe it's time to send RSI a wish list. Here are a few items 
> I've thought of. At least some have been mentioned in the newsgroup 
> before.
> 
> ... eight requests deleted ...


I agree with what's been said so far.  How about a few more requests,
in increasing order of drastic-ness.  These are still mostly
language-completeness issues, not feature requests.

1. Procedures and functions which do not accept any keywords, should
   at least accept _EXTRA=<undefined>.  At the moment IDL crashes
   when this happens.

2. CONGRID() returns interpolates which are off by half a pixel.
   I argue this is incorrect, and it should be fixed.

3. An interrogation routine to determine whether a file is open or
   not.  HELP, /FILES is not enough

4. Additional keyword to MAKE_ARRAY, DBLARR, etc, which enforces strict
   dimensions.  The final dimension should not be dropped!

5. Ability to query current line number and filename, for reporting
   error messages.  The HELP procedure is sometimes overkill.

6. Ability to implicitly index an array relative to its last element:
     a(0:*-2) = 1   ; sets all but last two elements to 1

7. The WHERE() function

   * should return a NULL value upon request, instead of -1.
     a(NULL) = 1  ; would have no effect

   * should have a COMPLEMENT keyword, to return indices of 
     array elements that fail the test.

     A_IS_1 = WHERE( A EQ 1, COMPLEMENT=A_NOT_1)

     This can save performing WHERE() twice on large arrays.

8. Ability to access strings as arrays, rather than with STRMID()
   and STRPUT.

Craig


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