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How to find second minimum and maximum in 3D array? [message #90353]

Wed, 25 February 2015 12:01

Harald Frey
Messages: 41
Registered: March 1997

Member

I have a time series of ~200 images with dimensions [X,Y]=[400,250]. My data is a UINTARR[200,400,250]. It is very easy to get the minimum and maximum for each pixel X,Y in my time series using

res=min(array,dimension=1,max=max_val)
IDL> help,res,max_val
RES FLOAT = Array[400, 250]
MAX_VAL FLOAT = Array[400, 250]

However, several pixels have 0 value or 65535 value and I want the second minimum and second maximum which are not 0 or 65535. I can do this in a for-loop, but is there a more clever and faster way?

min_array=uintarr(400,250)
max_array=uintarr(400,250)
for x=0,400-1 do begin
for y=0,300-1 do begin
good=where (array[*,x,y] gt 0 and array[*,x,y] lt 65535l)
res=min(array[good,x,y],dimension=1,max=max_val)
min_array[x,y]=res
max_array[x,y]=max_val
endfor
endfor

Thanks,
Harald Frey (UC Berkeley)

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[Message index]

		How to find second minimum and maximum in 3D array? By: Harald Frey on Wed, 25 February 2015 12:01
		Re: How to find second minimum and maximum in 3D array? By: Craig Markwardt on Wed, 25 February 2015 13:25
		Re: How to find second minimum and maximum in 3D array? By: Harald Frey on Wed, 25 February 2015 13:31

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