how to do this calculation not by 'for' cycle?

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I have the below data:
data =[...
1.0000 1.0000 1.0000 53.1100;...
1.0000 2.0000 2.0000 59.0900;...
2.0000 1.0000 2.0000 71.3100;...
2.0000 2.0000 1.0000 70.2400]
Now I want to get a 'variable'--Data as below:
Data=[53.11+59.09 53.11+71.31 53.11+70.24;
71.31+70.24 59.09+70.24 59.09+71.31]
I can get 'Data' by 'for' cycle function but I want to do this work by other better method.
The addition logic is that:
take column 2 of data for example, both data(1,2) and data(3,2) equal 1.0000, so add data(1,4) and data(3,4) to get Data(1,2).

Risposta accettata

Guillaume
Guillaume il 15 Dic 2015
One possible way to do it:
data = [1 1 1 53.1100
1 2 2 59.0900
2 1 2 71.3100
2 2 1 70.2400];
%first split data into two matrices for easier referencing:
rowdest = data(:, 1:end-1);
rowvals = data(:, end);
%second create matrix of column indices
coldest = repmat(1:size(rowdest, 2), size(rowdest, 1), 1);
%third use accumarray to compute the sum:
newdata = accumarray([rowdest(:) coldest(:)], repmat(rowvals, size(rowdest, 2), 1))

Più risposte (1)

Stephen23
Stephen23 il 15 Dic 2015
Modificato: Stephen23 il 15 Dic 2015
This is easy using accumarray:
inp = [1,1,1,53.1100;1,2,2,59.0900;2,1,2,71.3100;2,2,1,70.2400]
out(:,3) = accumarray(inp(:,3),inp(:,4));
out(:,2) = accumarray(inp(:,2),inp(:,4));
out(:,1) = accumarray(inp(:,1),inp(:,4))
and the result is:
out =
112.20 124.42 123.35
141.55 129.33 130.40
and your example output is:
>> [53.11+59.09,53.11+71.31,53.11+70.24;71.31+70.24,59.09+70.24,59.09+71.31]
ans =
112.20 124.42 123.35
141.55 129.33 130.40
  1 Commento
Guillaume
Guillaume il 15 Dic 2015
If data is always three columns of indices + one column of number, this works. If the size of data is not fixed, my answer is more generic.

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