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Re: newbie question on array manipulation [message #66290 is a reply to message #66287]

Tue, 05 May 2009 04:53

ben.bighair
Messages: 221
Registered: April 2007

Senior Member

On May 5, 7:40 am, jpardila <blu...@gmail.com> wrote:
> What is the best way to manipulate one array and remap its values
> according to conditions?
> Let's say I have a 2-d array, for all the elements equal to 5 I want
> to change their values to 0. For values equal to 10 I want to convert
> to 1 and so on. I am really confused and don't know if to use IF,
> where, for or while. Thanks for answering this basic one.
> JP

Hi,

The simplest is to use where - don't forget to use the output COUNT
argument shown here as "na".

a = WHERE(array EQ 10, na)
if (na GT 0) then array[a] = 1

If you are doing a multiple replacements (of different values) in a
single array then you'll want to strap your sneakers on and use
HISTOGRAM with it's REVERSE_INDICES output keyword. See
http://dfanning.com/tips/histogram_tutorial.html for more on that - it
is the swiss knife of IDL.

CHeers,
Ben

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[Message index]

		Re: newbie question on array manipulation By: jpardila on Tue, 05 May 2009 23:54
		Re: newbie question on array manipulation By: ben.bighair on Tue, 05 May 2009 06:24
		Re: newbie question on array manipulation By: Jean H. on Tue, 05 May 2009 06:06
		Re: newbie question on array manipulation By: ben.bighair on Tue, 05 May 2009 04:53

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