How to rearrange values in a matrix

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afrya
afrya 2013-11-4
评论： afrya 2014-4-6
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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采纳的回答

Sean de Wolski
Sean de Wolski 2013-11-4
There are a few elegant ways to do this. I would use accumarray
data = [
1 1 5
1 2 6
1 3 7
2 1 8
2 2 9
2 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
afrya 2013-11-4
When I'm working with decimal numbers,I have the following error
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
>> 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?

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更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2013-11-4
编辑：Andrei Bobrov 2013-11-4
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];
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Andrei Bobrov
Andrei Bobrov 2014-4-5
another variant of last row
out = [nan,rc{2}',nan;rc{1},v,accumarray(c1{1},x(:,3),[],@mean)];
afrya
afrya 2014-4-6
Thanks for your help, it works now

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