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Re: Array definition [message #55273 is a reply to message #55271]

Wed, 08 August 2007 10:38

Conor
Messages: 138
Registered: February 2007

Senior Member

On Aug 8, 1:18 pm, Yaswant Pradhan <Yaswant.Prad...@gmail.com> wrote:
> On Aug 8, 6:00 pm, Melanie <mkjone...@gmail.com> wrote:
>
>> Hi,
>> I am trying to check an array of about 19000 elements for values that
>> are above a certain value. I then want to save only the index of the
>> larger values in a new array.
>
> avoid FOR loop, use WHERE
> indices = where(array GT value, n_wh)
>
>
>
>> So, I am going through the original array with a for loop and checking
>> if each value is greater than 19:
>> for i=0, nelements-1 do begin
>> if (array1[i] gt 19) then...
>
>> Next, if the value in array1 is in fact greater than 19, I want to
>> save the value of i into a new array such as
>
>> if(array1[i] gt 19) then array2[...]=i
>
>> But I'm not sure how to make this work such that I can write each
>> subsequent i value for which the value in array1 is gt 19 into each
>> subsequenbt space in array2...
>
>> Any ideas? Please let me know if this question is not clear...

specifically:

array_size = size(array1, /dimensions)
array2 = fltarr(array_size)
w = where( array1 gt value, c )
if c gt 0 then array2[w] = array1[w]

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[Message index]

		Re: Array definition By: Bob[3] on Wed, 08 August 2007 10:53
		Re: Array definition By: Conor on Wed, 08 August 2007 10:38
		Re: Array definition By: yp on Wed, 08 August 2007 10:18
		Re: Array definition By: Bob[3] on Wed, 08 August 2007 10:15

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