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Re: Indexing structures of different type

Donglai Gong Rm3110 x1569 <donglai@eden.rutgers.edu> writes:
> Hi, does anyone know how to index structures of different types in IDL?
> REPLICATE won't work since it creates an array of the same structure, so
> I'm thinking of doing a structure of structures.  However I don't know
> how to index them for use in a loop.  Thanks in advance.

If you are *really* trying to glue a bunch of different types
together, you should probably structures as you say.

How to loop over them?  This is easily done with a little magic:

;; Initialize your structure
s = {u:0L, v:0D, w:intarr(5), x:{a:1, b:2}, y:'hello'}

n = n_tags(s)
for i = 0L, n-1 do begin
  ;; The magic is here:
  f = s.(i)

  ;; Operate on f here:
  print, f

However, you should be aware that IDL structures are pretty slow to
operate on, especially when you build large ones.  [ Some versions of
IDL have a limit on the number of elements in a structure too. ]

Good luck,

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