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Re: make all array values equal to zero [message #89862 is a reply to message #89861]

Thu, 11 December 2014 08:59

lecacheux.alain
Messages: 325
Registered: January 2008

Senior Member

On Thursday, December 11, 2014 4:58:37 PM UTC+1, Mike Galloy wrote:
> On 12/11/14, 8:12 am, g.nacarts@gmail.com wrote:
>> Hi
>>
>> Can I use the "greater than" operator to make all array values
>> greater than 100 equal to zero?
>>
>> E.g. A = [[1,2,3],[120,4,200]] to become A = [[1,2,3],[0,4,0]]
>>
>> Many Thanks
>>
>
> In addition to the other methods mentioned:
>
> IDL> print, (A le 100) * A
> 1 2 3
> 0 4 0
>
> And, if you really want to know if there was some way to do it with
> greater than operator, yes you can:
>
> IDL> print, (1B - (A gt 100)) * A
> 1 2 3
> 0 4 0
>
> Mike
> --
> Michael Galloy
> www.michaelgalloy.com
> Modern IDL: A Guide to IDL Programming (http://modernidl.idldev.com)
> Research Mathematician
> Tech-X Corporation

IDL> A=randomn(rien,10000000)
IDL> tic & A *= (A gt 1) & toc
% Time elapsed: 0.078000069 seconds.
IDL> tic & A[where(A gt 1,/NULL)]=0 & toc
% Time elapsed: 0.047000170 seconds.

The "where" solution appears to be somewhat faster.

alx.

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[Message index]

		make all array values equal to zero By: g.nacarts on Thu, 11 December 2014 07:12
		Re: make all array values equal to zero By: lecacheux.alain on Thu, 11 December 2014 07:20
		Re: make all array values equal to zero By: Helder Marchetto on Thu, 11 December 2014 07:20
		Re: make all array values equal to zero By: Michael Galloy on Thu, 11 December 2014 07:58
		Re: make all array values equal to zero By: lecacheux.alain on Thu, 11 December 2014 08:59
		Re: make all array values equal to zero By: Michael Galloy on Thu, 11 December 2014 09:52
		Re: make all array values equal to zero By: g.nacarts on Fri, 12 December 2014 06:54

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