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Re: Removing repeating array values [message #48104 is a reply to message #48103]

Tue, 28 March 2006 12:43

savoie
Messages: 68
Registered: September 1996

Member

David Fanning <davidf@dfanning.com> writes:

> Jonathan Wolfe writes:
>
>> Is there an easier way than a for loop to remove repeating values
>> within an array? For example, I have two arrays and am trying to match
>> the closest value from one with the other using a where() statement.
>> When the where statement is returned, I have multiple instances of the
>> same value; however, I just want to keep one of these. A for loop
>> works, but computing speed is slow, I'm running on an old 700MHz PIII.
>> Do you know of a faster way? Thanks for the help!
>
> Removing elements from an array is tailor-made for
> the HISTOGRAM function. See the Histogram Tutorial for
> an example:
>
> http://www.dfanning.com/tips/histogram_tutorial.html
>
> Cheers,
>
> David

I responded privately at first, but thought other people might want this too.

Is UNIQ what you're looking for?
from the manual...
; Create an array:
array = [1, 2, 1, 2, 3, 4, 5, 6, 6, 5]

; Variable B holds an array containing the sorted, unique values in
; array:
b = array[UNIQ(array, SORT(array))]
PRINT, b
IDL prints

1 2 3 4 5 6

It might be faster than learning histogram :)

Just a thought.

Matt

--
Matthew Savoie - Scientific Programmer
National Snow and Ice Data Center
(303) 735-0785 http://nsidc.org

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[Message index]

		Re: Removing repeating array values By: mmeron on Tue, 28 March 2006 13:26
		Re: Removing repeating array values By: David Fanning on Tue, 28 March 2006 13:02
		Re: Removing repeating array values By: vorticitywolfe on Tue, 28 March 2006 12:50
		Re: Removing repeating array values By: savoie on Tue, 28 March 2006 12:43
		Re: Removing repeating array values By: mchinand on Tue, 28 March 2006 12:40
		Re: Removing repeating array values By: David Fanning on Tue, 28 March 2006 12:30

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