sum values of histogram bins
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john Chandler
am 28 Mai 2014
Bearbeitet: Image Analyst
am 28 Mai 2014
Hi, I have data on particle intensities. I am binning the particles into bins based upon the intensities. This code is working.
histBins=[10, 25, 50, 75, 100, 150, 200];
a=hist(d,histBins);
I will now like to sum up the intensity of all the particles in each bin. Is there a way to do this?
Thanks, John
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Sean de Wolski
am 28 Mai 2014
Building on The Cyclist's answer, use accumarray to do the summing:
x = randn(100,1);
edges = -10:10;
[~, idx] = histc(x,edges);
binsums = accumarray(idx,x)
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Image Analyst
am 28 Mai 2014
Bearbeitet: Image Analyst
am 28 Mai 2014
No need to mess with histograms, and resulting loss of precision. If you want "sum up the intensity of all the particles", just sum the particles themselves, not the histogram bins.
sumOfAllParticleIntensities = sum(d);
If you want the sums of all particle intensities bin by bin between the bin edges that you gave, then you can do this:
histBins=[10, 25, 50, 75, 100, 150, 200];
x = 200*randn(100,1);
for k = 1 : length(histBins)-1
indexes = x > histBins(k) & x <= histBins(k+1);
binByBinSums(k) = sum(x(indexes));
end
% Print to command window:
binByBinSums
This will be more accurate than doing anything based on counts and the values of the bin centers.
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the cyclist
am 28 Mai 2014
Bearbeitet: the cyclist
am 28 Mai 2014
If you change your code to use the histc() command instead of the hist() command, then you can do
[count,idx] = histc()
will give you the index to which bin each element was sorted into. You can use that index sum the intensities in each bin.
[histc() specifies the bins based on edges, rather than centers.]
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