Calculate % difference for 2 vectors into a matrix
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Coulter Johnston
on 3 Mar 2022
Edited: Alberto Cuadra Lara
on 3 Mar 2022
Hi,
I have two vectors of average firing rates of the same population of neurons when exposed to different stimuli. These vectors are both the same size (1x158). I want to create a matrix that would be 158x158 of the percentage difference between each of the firing rates, then make a heatmap of this matrix. Is there any function that could help to directly make this matrix? I have used the following code so far to try to calculate the percentage difference, but it doesnt seem to be working correctly as the values in each column of the matrix are all the same:
diffMat = zeros(length(FR),length(FR2));
for i = 1:length(FR)
for j = 1:length(FR2)
diffMat(i,j) = abs(FR2(j)-FR(i)./FR(i))*100;
end
end
2 Comments
Matt J
on 3 Mar 2022
but it doesnt seem to be working correctly as the values in each column of the matrix are all the same:
You should run that test for us (here, not on your local computer) so we can see what you mean. For now, all we can do is assume that FR2 has been made all zeros by mistake.
Alberto Cuadra Lara
on 3 Mar 2022
Edited: Alberto Cuadra Lara
on 3 Mar 2022
Hello Coulter,
I know you already have your answer. The error here was in your definition of diffMat. The parentheses are missing; otherwise FR(i)./FR(i) is 1, so you'll always get the same row values.
% Data
N = 3;
FR = randn(1, N);
FR2 = randn(1, N);
% Original
diffMat = zeros(length(FR),length(FR2));
for i = 1:length(FR)
for j = 1:length(FR2)
diffMat(i,j) = abs(FR2(j)-FR(i)./FR(i))*100;
end
end
diffMat
% Correct
for i = 1:length(FR)
for j = 1:length(FR2)
diffMat(i,j) = abs((FR2(j)-FR(i))./FR(i))*100;
end
end
diffMat
% Best approach
diffMat = abs(1 - FR2./FR')*100
Accepted Answer
More Answers (1)
David Hill
on 3 Mar 2022
FR1=rand(1,158);FR2=rand(1,158);
[fr1,fr2]=meshgrid(FR1,FR2);
percentDifference=(fr2-fr1)./fr1*100;
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