finding all indices of a value in matrix

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sambhav jain
sambhav jain 2020-2-18
评论： sambhav jain 2020-2-18
i have a matrix say
[2 2 3 ;
2 4 2;
2 3 2]
how do i find all the indices (row, column) of 2 (minimum value element of matrix) in the given matrix?
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Stephen23
Stephen23 2020-2-18
"but could you plz tell how is it better by not using find?"
It isn't better, it just demonstrates that every problem can be approached in different ways, and hopefully shows a different way to think about the problem.

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采纳的回答

Rafael Hernandez-Walls
A=[2 2 3 ;
2 4 2;
2 3 2];
[r,c]=find(A==min(A))
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Stephen23
Stephen23 2020-2-18
编辑：Stephen23 2020-2-18
min(A)
should be
min(A(:))
otherwise this code will fail for any matrix which does not contain the minimum value in each column.

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更多回答（1 个）

Steven Lord
Steven Lord 2020-2-18
Do you need the locations or do you simply need to refer to the locations where the specified value occurs? Those are two slightly different things. If the latter, you don't need to use find and don't need to compute the indices at all.
Use logical indexing.
A = [2 2 3 ; 2 4 2; 2 3 2]
B = A; % Make a copy of A for future reference
two = A == 2 % Create a logical mask
B(two) = -1 % Replace all 2's in (the copy of) A with -1
In this example, I don't care where the 2's were in A. I only cared that I could change those elements.
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sambhav jain
sambhav jain 2020-2-18
I first found the minimum value in the matrix and then found the indices of the value using above as given by rafael but yours works too. Thank you

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