Summing up subsequent rows if equal

1 次查看（过去 30 天）
neil vaz
neil vaz 2023-7-19
评论： neil vaz 2023-7-19
well, I have been trying to sum up the values of the third column if the values of the rows (considering values in the first and second column only) tare equal. But couldnt suceed. It would be of great help if anyone would help me out with it.
A = [ 2 3 5
3 4 5
2 3 5
3 4 5
5 6 6
2 3 5
5 6 6
3 4 5 ];
The code i wrote is as follows
m,n] = size (A);
for i = 1:(m-1)
BB=[];
for j = i+1:(m)
if A(i,1)== A(j,1)
if A(i,2)== A(j,2)
B(i)= A(i, 3)+ A(j,3)
BB(k)=[A(i,1),A(i,2),BB(k)+B(i)]
end
end
end
end
The result I need is as follows
BB= [ 2 3 15
3 4 15
5 6 12 ];

请先登录，再回答此问题。

采纳的回答

Dyuman Joshi
Dyuman Joshi 2023-7-19
编辑：Dyuman Joshi 2023-7-19
Ran in:
There is another approach you can follow -
A = [ 2 3 5
3 4 5
2 3 5
3 4 5
5 6 6
2 3 5
5 6 6
3 4 5];
%Get the unique combinations of rows from the first two columns
%and the rows they are in
[B,~,rowidx] = unique(A(:,1:2),'rows')
B = 3×2
2 3 3 4 5 6
rowidx = 8×1
1 2 1 2 3 1 3 2
%Get the sum of values (i.e. 3rd column of A) corresponding to same indices
S = accumarray(rowidx,A(:,3))
S = 3×1
15 15 12
%Final output
Out = [B S]
Out = 3×3
2 3 15 3 4 15 5 6 12

更多回答（3 个）

Angelo Yeo
Angelo Yeo 2023-7-19
Ran in:
A = [2 3 5
3 4 5
2 3 5
3 4 5
5 6 6
2 3 5
5 6 6
3 4 5 ];
kindOfRowVec = unique(A(:, 1:2),'rows');
BB = [kindOfRowVec, zeros(size(kindOfRowVec, 1), 1)];
for i_kind = 1:size(kindOfRowVec, 1)
idx = any(A(:, 1:2) == kindOfRowVec(i_kind, :), 2);
BB(i_kind, 3) = sum(A(idx, 3));
end
BB
BB = 3×3
2 3 15 3 4 15 5 6 12
Diya Tulshan
Diya Tulshan 2023-7-19
Hii Neil Vaz,
I understand you want to debug the code and get the desired output.
Here's a solution that might help:-
A = [2 3 5;
3 4 5;
2 3 5;
3 4 5;
5 6 6;
2 3 5;
5 6 6;
3 4 5];
% Extract the first two columns
first_two_cols = A(:, 1:2);
% Get unique combinations of the first two columns
unique_combinations = unique(first_two_cols, 'rows', 'stable');
% Initialize the sumvalues array
sumvalues = zeros(size(unique_combinations, 1), 1);
% Loop through each unique combination
for i = 1:size(unique_combinations, 1)
% Find the rows that match the current unique combination
matching_rows = all(first_two_cols == unique_combinations(i, :), 2);
% Sum the corresponding values from the third column
sumvalues(i) = sum(A(matching_rows, 3));
end
% Combine the unique combinations with the summed values
finalvalue= [unique_combinations, sumvalues];
You will be able to see the desired output in the workspace when you run the above code.
Kindly refer to the link below to get a good overview about the function that i have used:
unique:- https://in.mathworks.com/help/matlab/ref/double.unique.html
Hope it helps!
Chunru
Chunru 2023-7-19
Ran in:
A = [ 2 3 5
3 4 5
2 3 5
3 4 5
5 6 6
2 3 5
5 6 6
3 4 5 ];
[C, ia, ic] = unique(A(:, 1:2), 'rows');
D = [C zeros(size(C,1), 1)];
for i=1:size(C, 1)
D(i, 3) = sum(A(ic==i, 3));
end
D
D = 3×3
2 3 15 3 4 15 5 6 12

类别

在 Help Center 和 File Exchange 中查找有关 Graph and Network Algorithms 的更多信息

标签

产品


版本

R2021a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by