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Re: Last bin of a histogram ? [message #83890 is a reply to message #83889]

Wed, 10 April 2013 10:50

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

John Correira writes:

> I'm trying to understand why HISTOGRAM selects the bins it does. The
> final part I don't understand is the last bin. Here is an example
>
> ; some fake data
> data = RANDOMU(systime(1),1000)*100
>
> ; make sure there are some values in the last bin
> while N_ELEMENTS(where(data ge 99.5 AND data lt 100.,count)) do $
> data = RANDOMU(systime(1),1000)*100
>
> ; how many points fall in the last bin?
> print, count
>
> h = histogram(data,min=9.5,max=99.5,binsize=.5,locations=locs)
> nbins = n_elements(h)
>
> ; starting locations of the last few bins
> print, locs[nbins-5:nbins-1]
>
> ; how many points in the last few bins
> print, h[nbins-5:nbins-1]
>
> Why is the last bin returned by the HISTOGRAM function zero? According
> to the help, the LOCATIONS keyword returns "the starting locations for
> each bin", so to my mind the last bin should include values that fall
> between locations[-1] and locations[-1]+binsize. I must be missing
> something obvious but I can't see it.

It seems to me you are missing the fact that you set MAX=99.5 in the
HISTOGRAM command. Or, am I missing something?

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		Re: Last bin of a histogram ? By: John Correira on Wed, 10 April 2013 11:20
		Re: Last bin of a histogram ? By: David Fanning on Wed, 10 April 2013 11:08
		Re: Last bin of a histogram ? By: John Correira on Wed, 10 April 2013 11:02
		Re: Last bin of a histogram ? By: David Fanning on Wed, 10 April 2013 10:50

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