MATLAB Answers

Calculate weighted average of a 2D matrix

152 views (last 30 days)
Dear all, I hope all is well. I am working with a 2D Matrix that is 376x481. I would like to calculate the weighted average of this matrix for each row, such that the desired output should be sized 376 X 1. I would greatly appreciate any help with this problem.
Thanks.

  0 Comments

Sign in to comment.

Accepted Answer

James Tursa
James Tursa on 7 Aug 2018
E.g.,
w = 1x481 vector of weights
M = your 376x481 matrix of values
result = sum(M.*w,2) / sum(w);
or
sum(bsxfun(@times,M,w),2) / sum(w);

  5 Comments

Show 2 older comments
Abdul Wahab
Abdul Wahab on 8 Aug 2018
Thank you for your detailed answer. I am currently trying to figure out the weight vector of all the row elements in a 376 x 481 matrix. I guess I should have phrased the question differently. Is there a way to calculate the weight vector as such?
James Tursa
James Tursa on 8 Aug 2018
Can you provide us with some info on what data this matrix contains and how it was generated? Then maybe we can make a stab at what you might want to do for weights.
Abdul Wahab
Abdul Wahab on 8 Aug 2018
This matrix is populated with a non-dimensional variable (376 rows) and associated time history of 481 hours. So each row is then a representation of how this non-dimensional variable is changing through 481 hours (one column for every hour). This non-dimensional number varies in a specific order where it contains both unique and non-unique values of this non-dimensional variable. I would like to figure out the weight vector of the non-unique and unique values in every row and get the weighted average instead of a simple mean. I hope this provides some more insight into my problem.

Sign in to comment.

More Answers (1)

Thorsten
Thorsten on 8 Aug 2018
X = rand(376, 481);
w = rand(1, size(X, 2));
Xw = bsxfun(@times, X, w);
m = mean(Xw, 2);

  1 Comment

stelios loizidis
stelios loizidis on 23 May 2019
Hello,
I saw the commands you wrote above and I have the following question; I have a matrix e.g
[ 5 3 3 1
3 4 5 2
5 0 0 0
3 4 5 2 ]
For this matrix I have to make a weighted average for each row. That is [5+3+(4/5)*(3+1)] / 4 =16/5. Also, if there is only one number and the rest zero (row 3) the weighted average should be [5+0+0+0]/ 1 =5 and the end we choose the largest weight average. How does this work?

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by