loop of Column Average

Question

Arvind Gauns 2022-4-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1699710-loop-of-column-average

评论： Arvind Gauns 2022-4-19

采纳的回答： Davide Masiello

I have a matrix of 1024 * 78.(datatype: double )

I want to average every two columns such that the resultant matrix must be 1024*39. (average of every two matrix)

how to get it done?

again for time being if i dont know the number of columns (due to huge dataset) and want to run a loop for averaging the columns for the similar case as mentioned about, what will be the changes in the code ?

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Answer 1

Davide Masiello 2022-4-19

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编辑：Davide Masiello 2022-4-19

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There's no need to use a for loop.

Try the code below.

clear,clc
A = rand(1024,78);                      % initial matrix of doubles
B = (A(:,1:2:end-1)+A(:,2:2:end))/2;    % matrix of averages for each two columns
size(B)
ans = 1×2
        1024          39

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Arvind Gauns 2022-4-19

Thank you @Davide Masiello.

it works

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Answer 2

Eric Delgado 2022-4-19

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Hi @Arvind Gauns, just pass your input matrix to the function below. Hope it helps! :)

function outMatrix = Fcn_twoColumnsMean(inMatrix)
    arguments
        inMatrix (1024,:) {mustBeNumeric} = randn(1024, 78)
    end
        
    NN = floor(width(inMatrix)/2);
    outMatrix = zeros(1024, NN);
    
    for ii = 1:NN
        outMatrix(:,ii) = mean(inMatrix(:,2*ii-1:2*ii), 2);
    end
    
end

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Eric Delgado 2022-4-19

For sure! Especially if the script is becoming too big. So... you have to create modules for debugging purposes. But at the end of the day, it's your call! :)

Arvind Gauns 2022-4-19

in that case i need not need to call the function right ?

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