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Re: Histogram and bin sizes [message #59211 is a reply to message #58869]

Thu, 06 March 2008 16:14

lyle_pakula
Messages: 2
Registered: March 2008

Junior Member

On Feb 22, 1:54 am, "Kenneth P. Bowman" <k-bow...@null.edu> wrote:

>
>
> times slower than usingHISTOGRAMwith regular bins due to the time
> required to do a binary search.
>
> ;UseHISTOGRAMto bin 10^7 numbers with evenly-spaced bins
>
> r = 100.0*RANDOMU(seed, 10^7)
> t0 = SYSTIME(/SECONDS)
> h1 =HISTOGRAM(r, MIN = 0.0, BINSIZE = 1.0)
> PRINT, 'Time for evenly-spaced bins : ', SYSTIME(/SECONDS) - t0
>
> ;Use VALUE_LOCATE andHISTOGRAMto bin 10^7 numbers
> ;with unevenly-spaced bins
>
> bins = [0.0, FINDGEN(99) + 0.1*RANDOMU(seed, 99)]
> t0 = SYSTIME(/SECONDS)
> i = VALUE_LOCATE(bins, r)
> h2 =HISTOGRAM(i, MIN = 0, BINSIZE = 1)
> PRINT, 'Time for unevenly-spaced bins : ', SYSTIME(/SECONDS) - t0

My first comp.lang.idl post ..

I think you may have to add nbins to the above histogram call as if
none of the elements lie in your desired bin range (i.e. value_locate
returns an array of -1's) histogram will not return a mapping into
your desired bin range.

e.g

function hist_ireg_bin, data, bin
; Calculate a histogram with irregular bin spacing
tmp = VALUE_LOCATE(bin, data)
return, HISTOGRAM(tmp, MIN = 0, BINSIZE = 1, nbins =
n_elements(bin))
end

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[Message index]

		Re: Histogram and bin sizes By: Conor on Thu, 21 February 2008 09:19
		Re: Histogram and bin sizes By: jeffnettles4870 on Thu, 21 February 2008 08:29
		Re: Histogram and bin sizes By: Conor on Thu, 21 February 2008 06:05
		Re: Histogram and bin sizes By: pgrigis on Wed, 20 February 2008 11:43
		Re: Histogram and bin sizes By: Kenneth P. Bowman on Thu, 21 February 2008 06:54
		Re: Histogram and bin sizes By: lyle_pakula on Thu, 06 March 2008 16:14
		Re: Histogram and bin sizes By: Kenneth P. Bowman on Thu, 21 February 2008 14:54
		Re: Histogram and bin sizes By: Conor on Thu, 21 February 2008 09:20

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