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Re: Simple question in IDL, looking for solution, thank you [message #81842 is a reply to message #81769]

Tue, 23 October 2012 15:21

Heinz Stege
Messages: 189
Registered: January 2003

Senior Member

On Tue, 23 Oct 2012 15:57:20 -0400, Jeremy Bailin wrote:

> A couple of notes:
>
> JBIU has a weighted histogram function:
> http://astroconst.org/jbiu/jbiu-doc/math/histogram_weight.ht ml
>

This is really great. I have learned something new again. Thank you,
Jeremy.

For the documentation: Jeremy's way of "chunk indexing" goes the
following way:

h=histogram(arr,min=0,reverse_indices=ri)
sum=lonarr(size(h,/dimensions))
for i=0l,n_elements(h)-1 do $
if h[i] gt 0 then sum[i]=total(bcg[ri[ri[i]:ri[i+1]-1]],/integer)
print,sum[1:*]

Small code, very fast, and low memory consumption. This is perfect.

Cheers, Heinz

> Regarding reverse_indices using lots of memory on sparse histograms: use
> VALUE_LOCATE!
> http://www.idlcoyote.com/code_tips/valuelocate.html
>
> -Jeremy.

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[Message index]

		Simple question in IDL, looking for solution, thank you By: Danxia on Mon, 22 October 2012 00:07
		Re: Simple question in IDL, looking for solution, thank you By: Heinz Stege on Tue, 23 October 2012 15:21
		Re: Simple question in IDL, looking for solution, thank you By: Heinz Stege on Tue, 23 October 2012 15:16
		Re: Simple question in IDL, looking for solution, thank you By: Jeremy Bailin on Tue, 23 October 2012 12:57

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