CODEWITHSUNDEEP
matlaboptimizationmatrixvectorizationmean
FF0605
FF0605

Reputation: 441

MATLAB: find means of other rows in a matrix without loop

I'm optimizing my codes. Now I have an MxN matrix, and I want to generate a mean MxN matrix which is the mean of other rows

for example: if i have matrix A:

1 2 3

3 4 5

2 3 2

In the new matrix B, I want each one is the mean of other rows.

mean(row2,row3)

mean(row1,row3)

mean(row1,row2)

I've think of many ways, but can't avoid a loop

    for row=1:3
        temp = A;
        temp(row,:) = [];
        B(row,:) = mean(temp);
    end

any thoughts?

Upvotes: 1

Views: 75

Answers (1)

Divakar
Divakar

Reputation: 221534

Simple with bsxfun -

B = (bsxfun(@minus,sum(A,1),A))./(size(A,1)-1)

The trick is to subtract the current row from the sum all rows with bsxfun in a vectorized manner, thus giving us the sum of all rows except the current one. Finally, get the average values by dividing them by the number of rows minus 1.

Upvotes: 2

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