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how to sum a group of gaussian distribution using "hist" ?

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Amr Hashem
Amr Hashem 2015-11-4
评论： Image Analyst 2015-11-5
I want to add five gaussian distributions at different points on x-axis
I try:
n=500;
H1 = normrnd(14,5,n,1); % generate random numbers of normal distribution at mu and sigma
H2 = 24+ normrnd(14,5,n,1); % start from 24
H3 = 48+ normrnd(14,5,n,1);
H4 = 72+ normrnd(14,5,n,1);
H5 = 96+ normrnd(14,5,n,1);
figure
hhh = [H1 H2 H3 H4 H5];
hist(hhh,130)
which produce a good figure as I need:
but I want to plot the total values of the intersected area. (I put a circle on them)
How I can sum them?

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采纳的回答

the cyclist
the cyclist 2015-11-4
编辑：the cyclist 2015-11-4
One simple possibility is to create one 2500x1 vector of the data rather than the 550x5 array you have, which is as simple as
hhh = [H1; H2; H3; H4; H5];
in place of
hhh = [H1 H2 H3 H4 H5];
If you do that, you will lose the distinct colors of the five histograms. But if you don't do it that way, you will have the problem of coloring the summed histograms, which gets tricky.
  2 个评论
Amr Hashem
Amr Hashem 2015-11-4
I used this code to change color for each:
hist(H,34)
h = findobj(gca,'Type','patch');
set(h,'FaceColor','b','EdgeColor','w')
but it changed all by the last color
Image Analyst
Image Analyst 2015-11-5
But with this method, you don't know which bins are in the "overlap/intersection" region and which are not. Determining "total values of the intersected area" was a requirement/request.

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更多回答（1 个）

Image Analyst
Image Analyst 2015-11-4
Try it like this, to sum the bins where both histograms are non-zero:
n=500;
H1 = normrnd(14,5,n,1); % generate random numbers of normal distribution at mu and sigma
H2 = 24+ normrnd(14,5,n,1); % start from 24
H3 = 48+ normrnd(14,5,n,1);
H4 = 72+ normrnd(14,5,n,1);
H5 = 96+ normrnd(14,5,n,1);
figure
hhh = [H1 H2 H3 H4 H5];
hist(hhh,130)
edges = -20:140;
counts1 = histc(H1, edges);
counts2 = histc(H2, edges)
counts3 = histc(H3, edges);
counts4 = histc(H4, edges);
counts5 = histc(H5, edges);
% Get indexes of first overlap region.
mask = counts1>0 & counts2>0;
% Sum both histograms in that area.
sum1 = sum(counts1(mask)) + sum(counts2(mask))
% Get indexes of second overlap region.
mask = counts2>0 & counts3>0;
% Sum both histograms in that area.
sum2 = sum(counts2(mask)) + sum(counts3(mask))
% Get indexes of third overlap region.
mask = counts3>0 & counts4>0;
% Sum both histograms in that area.
sum3 = sum(counts3(mask)) + sum(counts4(mask))
% Get indexes of fourth overlap region.
mask = counts4>0 & counts5>0;
% Sum both histograms in that area.
sum4 = sum(counts4(mask)) + sum(counts5(mask))
  2 个评论
Amr Hashem
Amr Hashem 2015-11-4
编辑：Amr Hashem 2015-11-4
it gives me the values of overlaped regions but nothing change in the figure (didn't plot them on the graph )
Image Analyst
Image Analyst 2015-11-5
I thought you could just use text() if you wanted some label on there, like
message = sprintf('The sum here = %d', sum1);
text(x,y,message);

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