How can I calculate the mean of a group of rows and put the in a matrix such as:
1 4 5
1 34 4
1 65 0
1 5 3
2 3 44
2 52 4
2 5 6
3 9 2
3 9 1
3 9 9
So I can have a matrix as
1 27 4
2 20 18
3 9 4
Thx
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OOzy Pal
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What defines a "group of rows"? Is it the value in the first column? – Floris May 12 '13 at 16:59
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@Shai Oh, these guys are sitting in the same CS class, I see. – May 12 '13 at 17:03
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2@H2CO3 and what a class it is... – Shai May 12 '13 at 17:04
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Hello, It is not a class. I have the power reading transferred from one station to another through transmission lines. The reading was taken every hour for the whole year. So I want to calculate the mean of power loss of every day. – OOzy Pal May 12 '13 at 17:14
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@H2CO3 What class is it? – OOzy Pal May 12 '13 at 17:18
1 Answers
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Assuming original data is in matrix A:
indx=unique(A(:,1));
for ii=1:numel(indx)
RowMean(ii,:)=mean(A(1,:)==indx(ii),:);
end
Floris
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2You can avoid the for loop by using the `accumarray` function, as [shown here](http://stackoverflow.com/questions/16086874#16087358)... – Eitan T May 12 '13 at 17:30
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@eitan you are right . This is "a" way, not the "best" way. Thanks for the link. – Floris May 12 '13 at 17:33