Use the transpose for your matrix and then apply find function to get the index for the actual matrix
How to switch the indexing order
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In matlab, the indexing for the find function numbers the matrix from top to bottom. However, for my code I need to run left to right. For exampe [1 ,2,3] etc.
Is there a different function I can use to achieve this?
Accepted Answer
the cyclist
on 15 Jun 2023
There's probably no way that isn't somewhat awkward, but here is a function that will convert a column-major index (which is what MATLAB uses) to a row-major linear index.
This assumes a 2-dimensional array, does no error checking, was untested on anything other than simple cases. (For example, didn't try empty arrays, etc.)
% Example use
% Some random matrix
M = rand(3,5);
% Use the function to find the 4th element in the first row, using row-major linear indexing
colMajorToRowMajor(4,M)
function rowMajorLinearIndex = colMajorToRowMajor(colMajorLinearIndex,M)
% Get input size
[MR,MC] = size(M);
% Convert
[cwr,cwc] = ind2sub([MC,MR],colMajorLinearIndex);
rowMajorLinearIndex = sub2ind(fliplr([MC,MR]),cwc,cwr);
end
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