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Re: help with - count in where() function [message #90872 is a reply to message #90868]

Fri, 01 May 2015 07:33

Phillip Bitzer
Messages: 223
Registered: June 2006

Senior Member

On Thursday, April 30, 2015 at 12:32:32 PM UTC-5, g.na...@gmail.com wrote:
> Hi
>
> I wrote a simple example of my code to understand the behaviour of count in the where() function but I still don't understand something.
>
> My example:
>
> array = [[-1,2,3,4,5],[6,-7,8,9,10]]
> mask =bytarr(5,5)
> for i=0L,4 do begin
> for j=0L, 4 do begin
> IF (TOTAL(ARRAY GT 5.)+ TOTAL(Array LT 0.)) EQ 0 THEN mask[i,j]=1
> endfor
> endfor
>
> ind = where(mask EQ 1,count)

>
> I was expecting the answers in the two last prints. I don't understand why when I print out the count it's zero.

Why do expect that to be the answer? Look at your loop again:

> for i=0L,4 do begin
> for j=0L, 4 do begin
> IF (TOTAL(ARRAY GT 5.)+ TOTAL(Array LT 0.)) EQ 0 THEN mask[i,j]=1
> endfor
> endfor

When, i=0, j=0, the total of `array GT 5` is 4 and the total of `array LT 0` is two.
When i=0, j=1, the total of `array GT 5` is 4 and the total of `array LT 0` is two.
When i=0, j=2, the total of `array GT 5` is 4 and the total of `array LT 0` is two.

See a pattern? ;-)

So, TOTAL(ARRAY GT 5.)+ TOTAL(Array LT 0.)) is never 0, as PaulV said.

Now, what exactly is the problem you're trying to solve?

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[Message index]

		help with - count in where() function By: g.nacarts on Thu, 30 April 2015 10:32
		Re: help with - count in where() function By: Paul Van Delst[1] on Thu, 30 April 2015 10:58
		Re: help with - count in where() function By: Phillip Bitzer on Fri, 01 May 2015 07:33

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