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

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Douglas 2014-8-18

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评论： Douglas 2014-8-18

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!

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Douglas 2014-8-18

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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Answer 1

Guillaume 2014-8-18

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在 MATLAB Online 中打开

Use the two arguments output of find (rather than find + ind2sub):

[y, x] = find(matrix);

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Douglas 2014-8-18

I went with this, seems the most straight-forward. Thank you!

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Answer 2

Iain 2014-8-18

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在 MATLAB Online 中打开

 Index_of_As = find( matrix );
 [down along] = ind2sub(size(matrix),Index_of_As);

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Answer 3

Adam 2014-8-18

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编辑：Adam 2014-8-18

在 MATLAB Online 中打开

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.