Converting a matrix of points to a list of x & y coordinates

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Hello,
I have a matrix of size n*n, filled with zeros. Some points are filled with A's. I'd like to take this matrix and turn it into two arrays, one with the x-coordinates of each A and the other with the y-coordinates of each A.
I have seen numerous ways of going the other way, i.e. from a list of coordinates to a matrix, but none going this way.
Any help is greatly appreciated!
  1 Comment
Douglas
Douglas on 18 Aug 2014
The reason I am looking to do this is to be able to use the scatter(X,Y) function to plot a sort of map of the matrix I have.
Is there perhaps a better way to do this?

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Accepted Answer

Guillaume
Guillaume on 18 Aug 2014
Use the two arguments output of find (rather than find + ind2sub):
[y, x] = find(matrix);

More Answers (2)

Iain
Iain on 18 Aug 2014
Index_of_As = find( matrix );
[down along] = ind2sub(size(matrix),Index_of_As);

Adam
Adam on 18 Aug 2014
Edited: Adam on 18 Aug 2014
ind1d = find( myMatrix == 'A' );
[y, x] = ind2sub( [n n], ind1d );
should be close to doing the job, although it depends what you mean by 'A'. Do you have a cell array? The above code would work if, instead of 'A', you had some numerical value, but otherwise it would likely need a bit of syntactical modification depending if you have a cell array.

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