Sum specific rows of an array
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yinki23
am 23 Jan. 2019
Beantwortet: s
am 23 Jan. 2019
Hi,
I have an array like:
0.2 2 3
1 3 4
1 4 6
0.8 4 6
2 5 1
1 6 2
0.4 6 2
Now I want to code that MATLAB sums up the values of the 1st column in the rows where the value of the 2nd and 3rd column match.
So the result should look like this below:
0.2 2 3
1 3 4
1.8 4 6
2 5 1
1.4 6 2
I hope someone can help me, thank you!
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Akzeptierte Antwort
Andrei Bobrov
am 23 Jan. 2019
A = [0.2 2 3
1 3 4
1 4 6
0.8 4 6
2 5 1
1 6 2
0.4 6 2];
[a,~,c] = unique(A(:,2:3),'rows','stable');
out = [accumarray(c,A(:,1)),a];
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s
am 23 Jan. 2019
clc;
clear all;
A = [0.2 2 3;1 3 4;1 4 6;0.8 4 6;2 5 1;1 6 2;0.4 6 2];
B = size (A,1);
Result = [];
n = 0;
for i = 1:1:B-1
if (A(i,2) == A(i+1,2) && A(i,3) == A(i+1,3))
n = n+1;
end
end
for j = 1:1:B-n
if (A(j,2) == A(j+1,2) && A(j,3) == A(j+1,3))
Sum = A(j,1)+A(j+1,1);
Result = [Result; Sum A(j,2) A(j,3)]
A([j+1],:) = [];
else
Result = [Result; A(j,1) A(j,2) A(j,3)]
end
end
This should help
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