I would like to filter out some vectors based on a percent of aggregate

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Jeff
Jeff 2013-9-22
I would like to filter some time series based on their weight of the overall aggregate. The weights are to be calculated based on the derived aggregate/components of the second last element in each vector (x1=20, x2=2, x3=62) The end result would be to extract the complete time series vectors satisfying the threshold. I would also appreciate suggested improvements to the code:
Threshold = *.2*
x1=[5 10 20 15 40 20 25]';
x2=[8 25 15 50 41 2 15]';
x3=[32 42 30 52 33 62 77]';
x=[x1 x2 x3];
sumx=sum(x')';
sumx=[sumx sumx sumx];
perx=x./sumx
perx=perx(4,:);
perx =
0.2381 0.0238 0.7381
Here x2 should be deleted since it falls below the threshold and a new object containing x1 and x3 vectors should get created.
x=[x1 x3];
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Jeff
Jeff 2013-9-22
Hi Image, you are on the right track thanks for your help. The one thing that was missing is that the threshold is based on the percentage that the second last element makes of the total of the three vectors along that element;
sumx=20+2+62 = 84 x1%=20/84=.2381 x2%=2/84=.0238 x3%=62/84=.7381
since threshold=.2 then x2%<threshold and x2 vector should be dropped;
Is that clearer?

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Image Analyst
Image Analyst 2013-9-22
编辑：Image Analyst 2013-9-22
See if this is what you want:
thresholdPercent = 0.2
x1=[5 10 20 15 40 20 25]';
x2=[8 25 15 50 41 2 15]';
x3=[32 42 30 52 33 62 77]';
% Sum them up
sumx = sum([x1,x2,x3], 2)
x=[];
% Get the value that each column will be compared to.
Threshold = thresholdPercent * sumx(end-1)
% Tack on x1 if it's above the threshold.
if x1(end-1) > Threshold
fprintf('Adding on x1:\n');
x = [x, x1]
end
% Tack on x2 if it's above the threshold.
if x2(end-1) > Threshold
fprintf('Adding on x2:\n');
x = [x, x2]
end
% Tack on x3 if it's above the threshold.
if x3(end-1) > Threshold
fprintf('Adding on x3:\n');
x = [x, x3]
end
% Get the means:
meanAcrossColumns = mean(x, 2)
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Image Analyst
Image Analyst 2013-9-22
It just prints out some debugging stuff to the command window - it's optional and you can remove it if you want.
Jeff
Jeff 2013-9-22
Hi Imagine, just implemented your code with actual data I have and one question that comes up is how do I know which variable has passed this threshold test? Is there a way to not only store that variable in object x but to name it as well so that I know which variable I have? Much appreciated

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Jeff
Jeff 2013-9-25
编辑：Jeff 2013-9-25
Found this in the matlab documentation just to share
Find the indices of values in a vector that are greater than a specified limit.
A = rand(1,10); limit = .75;
B = (A > limit); % B is a vector of logical values if any(B) fprintf('Indices of values > %4.2f: \n', limit); disp(find(B)) else disp('All values are below the limit.') end

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