Splitting a matrix into smaller matrices...
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I have a matrix 1000x3 matrix P which can be generated with the following code: (I call the columns of P: X, Y and Z)
P = [];
for X = 0.1:.1:1;
for Y = 0.01:.01:1;
Z = Y^2 + X;
P = vertcat(P, [X, Y, Z]);
end
end
I now want to create a matrix which contains all of the rows for which X = 0.5, say.
(This will be a 100x3 matrix in this example)
How do I do this?
Many thanks
D Howard
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Walter Roberson
am 20 Feb. 2012
M2 = P( P(:,1) == 0.5, : );
However, you need to read: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
3 Kommentare
Walter Roberson
am 20 Feb. 2012
Use unique() more directly.
[PU, PI, PJ] = unique(P(:,1));
PUC = length(PU);
for i = 1 : PUC
Q{i} = P(PJ == i, :);
end
Notice no floating point comparisons were used.
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