comp.lang.idl-pvwave archive: archive » Re: how to get index of array B data in array A

Home » Public Forums » archive » Re: how to get index of array B data in array A

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: how to get index of array B data in array A [message #14608 is a reply to message #14601]

Thu, 11 March 1999 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

Gary Fu (gfu@seadas.gsfc.nasa.gov) writes:

> Is there a simple way to get the index of the array B data in array A ?
>
> For example : A = [10,20,30,40,50], B = [10, 20, 33, 10, 30, 40, 9]
> I want like to get the index array of B in A [0, 1, -1, 0, 2, 3, -1]

I'm afraid you are stuck doing this in a loop because of
the way the WHERE function compares unequally-sized arrays.
But you can certainly do something like this:

A = [10,20,30,40,50]
B = [10, 20, 33, 10, 30, 40, 9]
C = Indgen(N_Elements(B))
FOR j=0, N_Elements(B)-1 do C[j] = (Where(A EQ B[j]))[0]
Print, C
0 1 -1 0 2 3 -1

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

Report message to a moderator

[Message index]

		Re: how to get index of array B data in array A By: davidf on Thu, 11 March 1999 00:00
		Re: how to get index of array B data in array A By: Gary Fu on Thu, 11 March 1999 00:00
		Re: how to get index of array B data in array A By: davidf on Thu, 11 March 1999 00:00

Previous Topic:	Re: File pointer problem on PC-IDL
Next Topic:	Re: GetColor Program

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sat Oct 11 08:35:59 PDT 2025

Total time taken to generate the page: 0.79721 seconds