I want to extract rows from my matrix that have a specific value in the second column.

Question

Philip Edwards 2023-7-5

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回答： Kavita Guddad 2023-7-5

I want to take all of the rows from a matrix that have a 1 in the second column and create a new matrix with these rows.

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Kavita Guddad 2023-7-5

在 MATLAB Online 中打开

x=[1 2 3 5;2 3 4 5;2 1 3 4;2 1 3 2 ];
y=[];
for i=1:size(x,1)
    if (x(i,2)==1)
        y=[y;x(i,:)];
    end
end
disp(x)
     1     2     3     5
     2     3     4     5
     2     1     3     4
     2     1     3     2
disp(y)
     2     1     3     4
     2     1     3     2

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Answer 1

Kavita Guddad 2023-7-5

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https://ww2.mathworks.cn/matlabcentral/answers/1992023-i-want-to-extract-rows-from-my-matrix-that-have-a-specific-value-in-the-second-column#answer_1267528

Hope this code does your job.

x=[1 2 3 5;2 3 4 5;2 1 3 4;2 1 3 2 ];

y=[];

for i=1:size(x,1)

if (x(i,2)==1)

y=[y;x(i,:)];

end

disp(x)

disp(y)

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Answer 2

Abhas 2023-7-5

3
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https://ww2.mathworks.cn/matlabcentral/answers/1992023-i-want-to-extract-rows-from-my-matrix-that-have-a-specific-value-in-the-second-column#answer_1267518

编辑：Abhas 2023-7-5

在 MATLAB Online 中打开

Hi Philip,

We can use logical indexing to select only the rows where the second column has a value of 1. The below code can solve your query:

% Sample input matrix
inputMatrix = [2, 1, 3; 
               4, 1, 6; 
               7, 0, 9; 
               1, 1, 2; 
               8, 1, 5];
% Find rows with a 1 in the second column
rowsWithOne = inputMatrix(inputMatrix(:, 2) == 1, :);