| Re: Mode function for floating point arrays [message #85119 is a reply to message #85114] |
Mon, 08 July 2013 01:01   |
Rob Klooster
Messages: 18
Registered: February 2013
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Junior Member |
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Hi Matthew,
Histogram also works on floating point arrays, you just need to set the binsize:
hist = histogram(array, binsize=epsilon, locations=locations)
mode = locations[where(hist eq max(hist))]
Note that for small values of epsilon, the resulting histogram array can become very large.
Regards,
Rob.
Op vrijdag 5 juli 2013 20:55:23 UTC+2 schreef Matthew Argall het volgende:
> PEAMBLE:
>
> I need a function that finds the mode of a floating point array. I have read David Fanning's article about integer arrays
>
>
>
> http://www.idlcoyote.com/code_tips/mode.html
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>
>
> From this article about majority voting, it seems like "Hist_ND" works for floating point values, but I have no experience with the magic of HISTOGRAM
>
>
>
> https://groups.google.com/forum/#!searchin/comp.lang.idl-pvw ave/Mode$20of$20a$20floating$20point$20array/comp.lang.idl-p vwave/YZK2ey-O5sE/9fLvx_AG2IAJ
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>
>
>
>
> QUESTION:
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> Here is my attempt. Can anyone make it better/faster?
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>
>
> ;-----------------------------------------------------
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> function mrmode, array, $
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> EPSILON=epsilon
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> compile_opt idl2
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>
>
> ;Number of points in ARRAY
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> npts = n_elements(array)
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>
>
> ;Default value for EPSILON
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> if n_elements(epsilon) eq 0 then epsilon = 1d-5
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>
>
> ;[index, count] for keeping track of mode statistics
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> mode_count = lonarr(2, npts)
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>
>
> ;Store first ~unique number. Count the how many ~unique numbers there are.
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> mode_count[*,0] = [0,1]
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> nunique = 1
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>
>
> ;Step through all points in ARRAY
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> for i = 1, npts - 1 do begin
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> match_found = 0
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>
>
> ;Try to pair the new point with other mode candidates
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> for j = 0, nunique - 1 do begin
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> if array[i] gt array[mode_count[0,j]]-epsilon && $
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> array[i] lt array[mode_count[0,j]]+epsilon $
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> then begin
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>
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> mode_count[1,j] += 1
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> match_found = 1
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> endif
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> endfor
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>
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> ;If no match was found, create a new mode candidate
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> if match_found eq 0 then begin
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> mode_count[*,nunique] = [i,1]
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> nunique += 1
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> endif
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> endfor
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>
>
> ;Get the mode
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> void = max(mode_count[1,*], iMode)
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> mode = array[mode_count[0,iMode]]
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>
>
> return, mode
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> end
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>
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>
>
> ;----------------------------------------------------------- ----------
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> ;Example Program (IDL> .r mrmode) /////////////////////////////////////////
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> ;----------------------------------------------------------- ----------
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> array = [1.2, 0.1, 3.3, 0.1, 2.0, 3.3, 4.8, 1.2, 0.1, 0.1, 6.7, 3.3]
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> mode = MrMode(array)
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> print, FORMAT='(%"The mode is: %f")', mode
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>
>
> end
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