How to normalize a matrix such that each column sums equal 1

Clarisha Nijman (view profile)

on 4 Oct 2018
Latest activity Commented on by Clarisha Nijman

on 4 Oct 2018

dpb (view profile)

Hello,
I have a matrix A=[1 2 3; 1 3 6] and want to normalize the matrix such that each column sum equals 1.
The normalized matrix should be: P=[0.5 0.4 0.33; 0.5 0.6 0.67]
I tried these codes:
P=normc(A);
P=(A)/sum(A,1);
P=A/norm(A,1);
but they do not result in a matrix with column sums 1.
Can somebody give me some feedback?
Clarisha

dpb (view profile)

on 4 Oct 2018

You're missing the "dot" operator so the division is matrix divide not element-wise. See
doc ./
doc rdivide % that's a stretch to know the function name, for sure... :)
A=A./sum(A);
Look up how Matlab operates on arrays in documentation for sum to see why this works for what you want with only one argument...

Clarisha Nijman

Clarisha Nijman (view profile)

on 4 Oct 2018
Thanks a lot, it worked!

Jim Riggs (view profile)

on 4 Oct 2018
Edited by Jim Riggs

Jim Riggs (view profile)

on 4 Oct 2018

[row, col] = size(A);
for i=1:col
P(:,i)= A(:,i)/sum(A(:,i))
end

Clarisha Nijman

Clarisha Nijman (view profile)

on 4 Oct 2018
Thanks a lot, this also works! Only a semicolon at the end of the third line.