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Re: replace elements in array [message #49001]

Sat, 10 June 2006 12:16

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

johnadams_1980@yahoo.com writes:

> How do you replace certain (common) elements in a array without using a
> for loop? For e. g., I have an array:
>
> a=[45,67,9999.,9999.,24]
>
> and would like to replace all the 9999. with 0.00 so that a becomes
>
> [45,67,0.00,0.00,24]
>
> (the array is huge, so changing each element individually is not an
> option).

Like this:

indices = Where(a EQ 9999.0, count)
IF count GT 0 THEN a[indices] = 0.00

Be aware that floating point numbers cannot be represented,
always, exactly with a computer, so you often have to look
for a value plus or minus a small delta.

http://www.dfanning.com/math_tips/razoredge.html

I can't tell from your example if you have floats with 9999.0
thrown in there with long integers, or what. (Maybe you aren't
sure, but you should be. It could make a difference in how you
go about finding the values.)

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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Re: replace elements in array

By: David Fanning on Sat, 10 June 2006 12:16

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