| Anyway to avoid this last for loop [message #64601] |
Thu, 08 January 2009 01:59 |
hldevil
Messages: 6
Registered: September 2008
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Junior Member |
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Hi Everybody,
after having worked my way through dfannings and jdsmiths histogram
tips I still haven't found a way to avoid one last (and time
consuming) FOR-loop. Maybe someone has an idea.
I have to lists (Millions of entries): one containing detector hit-
times, one containing anticoincidence hit-times. Only those detector
hits which do not have a AC event at the same time are supposed to be
kept.
I used a histogram approach:
;AClength is how many frames are thrown out after one AC Hit ->
multiple entries can fall into one bin
detHist=histogram(data,REVERSE_INDICES=ri, /L64, binSize=AClength)
acHist=histogram(ACdeletes, /L64, binSize=AClength)
;renormalize to one
dI=where(detHist GT 1, cntD)
aI=where(acHist GT 1, cntA)
IF cntD NE 0 THEN detHist[dI]=1
IF cntA NE 0 THEN acHist[aI]=1
;subtract the two histograms. All detector frames which have
corresponding AC frame should now have value 0, if AC frame exists but
not detector frame then value is -1. If only detector frame exists
(the ones we want) value stays 1!!!
diffHist=detHist-acHist
;keep the ones with one
keep=where(diffHist EQ 1, cnt)
;And now my problem. I need the indices of the keep-frames but there
can be more than one in a bin so I'm stuck with this loop:
FOR k=0L, cnt-1 DO BEGIN
keepIndices=[keepIndices,ri[ri[keep[k]]:ri[keep[k]+1]-1]]
ENDFOR
Is there any way I can avoid this, especially because it scales with
the number of hits which are kept.
Best Regards,
Steffen
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