Find mean and mean square root of each row in matrix without first row and column

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Ali Kareem 2015-11-2

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https://ww2.mathworks.cn/matlabcentral/answers/252359-find-mean-and-mean-square-root-of-each-row-in-matrix-without-first-row-and-column

评论： Star Strider 2015-11-2

Hi,

How I can find mean and mean square root of 10*10 matrix for each row in matrix and save them in matrix C(:,1) without including first row and column. for example if matrix A is 4*4

how I can find mean and mean square root of each row in matrix without including first row (1 3 3 4)and first column (1 2 8 2) in calculation?

I do not want to delete them from matrix because I need them later in my calculations.

Regards

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Answer 1

Star Strider 2015-11-2

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https://ww2.mathworks.cn/matlabcentral/answers/252359-find-mean-and-mean-square-root-of-each-row-in-matrix-without-first-row-and-column#answer_198196

在 MATLAB Online 中打开

I am guessing that you want the root mean square of the rows, as well as the arithmetic mean, omitting the first row and the first column.

This will do that:

A = [1  3  3  4
     2  5  7  6
     8  4  9  4
     2  1  6  9];
A_row_mean = mean(A(2:end, 2:end), 2)
A_row_rms = sqrt(mean(A(2:end, 2:end).^2, 2))

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Ali Kareem 2015-11-2

Hi,

Thank you for your reply. but some times in my matrix it is another row or column or more than one

How I can do that?

Regards

Star Strider 2015-11-2

在 MATLAB Online 中打开

Using your current matrix, if instead you wanted to eliminate columns 2 and 3 and row 3, the code changes to:

A_row_mean = mean(A([1:2 4], [1 4]), 2)                     % Without Row 3, And Without Columns 2 & 3
A_row_rms = sqrt(mean(A([1:2 4], [1 4]).^2, 2))

You have to specify the rows and columns you want to keep in the calculaton. Those you do not specify are not used.

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