normalization , colums, rows
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Dhurgham Al-karawi
on 26 May 2018
Edited: Dhurgham Al-karawi
on 26 May 2018
Hi everyone,
May I know which way correct to do normalization for a matrix by colums or rows?
Thanks.
2 Comments
Ameer Hamza
on 26 May 2018
The correct way depends on what you are trying to do, how are you normalizing etc. You need to specify what is your purpose for normalizing the matrix.
Accepted Answer
Jan
on 26 May 2018
Edited: Jan
on 26 May 2018
x = rand(242, 256),
xNRow = x ./ sum(x, 2); % Auto-expanding, Matlab >= R2016b
xNCol = x ./ sum(x, 1);
For older Matlab versions:
xNRow = bsxfun(@rdivide, x, sum(x, 2));
xNCol = bsxfun(@rdivide, x, sum(x, 1));
Now the rows or columns are normalized, such the the sum is 1.0. But perhaps you want the norm to be 1.0?
xNRow = x ./ vecnorm(x, 2); % Auto-expanding, vecnorm needs >= R2017b
xNCol = x ./ vecnorm(x, 1);
Or with older Matlab versions:
xNRow = x ./ sqrt(sum(x .* x), 2)); % Auto-expanding, >= R2016b
xNCol = x ./ sqrt(sum(x .* x), 1));
or again with bsxfun.
There are more methods for a "normalization": Set the mean to zero, and/or the std to 1 or such that the maximum peak height is 1.0. So you have to find out, what you need mathematically. Then the implementation in Matlab is easy.
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