How to rearrange values in a matrix

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afrya 2013-11-4

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评论： afrya 2014-4-6

采纳的回答： Sean de Wolski

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Hello, I have a large matrix with 3 columns(x,y,and z) and I want to rearrange the values inside this matrix. Example:

*Initial matrix

x y z

1 1 5

1 2 6

1 3 7

2 1 8

2 2 9

2 3 2

*Final matrix My goal is to rearrange the values of the matrix in this form

y
x 1 2 3
1 5 6 7 <-z values
2 8 9 2

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Sean de Wolski 2013-11-4

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There are a few elegant ways to do this. I would use accumarray

data = [
1 5
2 6
3 7
1 8
2 9
3 2];
V = accumarray(data(:,[1 2]),data(:,3))

Now V does not have the index values, but you already know them:

rr = 1:size(V,1)  %row
cc = 1:size(V,2)  %column

So I would just keep them separate.

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afrya 2013-11-4

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When I'm working with decimal numbers,I have the following error

x =

6000    0.6000    5.0000
6000    0.8000    6.0000
6000    0.9000    7.0000
8000    0.6000    8.0000
8000    0.8000    9.0000
8000    0.9000    2.0000

>> V = accumarray(x(:,[1 2]),x(:,3)) Error using accumarray First input SUBS must contain positive integer subscripts.

Do you know how to solve this problem?

Andrei Bobrov 2013-11-4

see my answer

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Andrei Bobrov 2013-11-4

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编辑：Andrei Bobrov 2013-11-4

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xyz = [1 1 5
1 2 6
1 3 7
2 1 8
2 2 9
2 3 2];
out = nan(max(xyz(:,1:2))+1);
out(2:end,1) = unique(xyz(:,1));
out(1,2:end) = unique(xyz(:,2));
out(2:end,2:end) = accumarray(xyz(:,1:2),xyz(:,3));

ADD

x =[    0.6000    0.6000    5.0000
0.6000    0.8000    6.0000
0.6000    0.9000    7.0000
0.8000    0.6000    8.0000
0.8000    0.8000    9.0000
0.8000    0.9000    2.0000];
[r,ii,ii] = unique(x(:,1));
[c,jj,jj] = unique(x(:,2));
v = accumarray([ii,jj],x(:,3));
out = [nan,c';r,v];