# How can I find X smallest numbers in a Matrix?

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Laila Kazemi am 2 Jul. 2013
I have a 480 by 640 matrix, and I would like to find 4 smallest number ( or closest values to zero).
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Matt J am 2 Jul. 2013
Xs=sort(X(:));
FourSmallest = Xs(1:4);
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Image Analyst am 2 Jul. 2013
You may have more than 4 pixels having the 4 smallest values. You can use ind2sub() or find
[rows1, columns1] = find(yourImage == Xs(1));
[rows2, columns2] = find(yourImage == Xs(2));
[rows3, columns3] = find(yourImage == Xs(3));
[rows4, columns4] = find(yourImage == Xs(4));
Matt J am 2 Jul. 2013
Bearbeitet: Matt J am 2 Jul. 2013
in Xind it return the indices as one number
In case it matters, note that the "one number" will work as an index, even when used with the original 480x640 matrix, e.g.,
>> X=reshape((1:20)*10,4,5).'
X =
10 20 30 40
50 60 70 80
90 100 110 120
130 140 150 160
170 180 190 200
>> [Xs, Xind]=sort(X(:));
>> X(Xind(4))
ans =
40

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