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Re: How do you sort an array in IDL? [message #11484 is a reply to message #11423]

Thu, 02 April 1998 00:00

Robert S. Hill
Messages: 11
Registered: January 1998

Junior Member

On Thu, 2 Apr 1998, Robert A. Lematta wrote:
> Does anyone know how to sort an array in idl (ala excell) while preserving
> the order of the other columns. For example, if I have a 10 by 10 array
> with the second column being time, how do I sort the entire array by time and
> have the values in the other columns follow. Like you'd do a sort in a
> spreadsheet. Please reply to lematta@spawar.navy.mil. Many thanks in advance.
> I've tried to figure out the sort function but I don't think it works on arraysswith more than one row or column.

You can do it with IDL's clever subscripting syntax:

Set up test data:

IDL> a = reverse(indgen(10))
% Compiled module: REVERSE.
IDL> b=indgen(10)+100
IDL> arr = transpose([[a],[b]])
IDL> print,arr
9 100
8 101
7 102
6 103
5 104
4 105
3 106
2 107
1 108
0 109

Sort on column 0:

IDL> col = arr(0,*)
IDL> s=sort(col)
IDL> arr2 = arr(*,s) ; sort on column, but apply sort to rows
IDL> print,arr2 ; voila
0 109
1 108
2 107
3 106
4 105
5 104
6 103
7 102
8 101
9 100

Bob

--
Robert.S.Hill.1@gsfc.nasa.gov Phone: 301-286-3624
Raytheon STX / Code 681, NASA/GSFC, Greenbelt, MD 20771

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[Message index]

		Re: How do you sort an array in IDL? By: Martin Schultz on Mon, 06 April 1998 00:00
		Re: How do you sort an array in IDL? By: Robert S. Hill on Thu, 02 April 1998 00:00
		Re: How do you sort an array in IDL? By: davidf on Thu, 02 April 1998 00:00
		Re: How do you sort an array in IDL? By: Liam Gumley on Thu, 02 April 1998 00:00
		Re: How do you sort an array in IDL? By: davidf on Thu, 02 April 1998 00:00

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