matrix addition according to position vector

2 次查看（过去 30 天）
Rabb
Rabb 2023-2-6
回答： Voss 2023-2-6
Hello, i have matrix A wich is 2xn dimension and vector b that is 1xn. I want to sort and sum A acording to vector b. for explamle
A=[1 3 5 7 9 11;
2 4 6 8 10 12]
b=[1 1 3 4 5 3]
so answer would be
C=[4 0 16 7 9
6 0 18 8 10]

请先登录，再回答此问题。

采纳的回答

Voss
Voss 2023-2-6
Ran in:
A=[1 3 5 7 9 11;
2 4 6 8 10 12];
b=[1 1 3 4 5 3];
Maybe something like this:
C = zeros(size(A));
ub = unique(b);
for ii = 1:numel(ub)
C(:,ub(ii)) = sum(A(:,b == ub(ii)),2);
end
disp(C);
4 0 16 7 9 0 6 0 18 8 10 0
Another way:
[bg,gidx] = findgroups(b);
C = zeros(size(A));
C(:,gidx) = splitapply(@(x)sum(x,2),A,bg);
disp(C);
4 0 16 7 9 0 6 0 18 8 10 0

更多回答（1 个）

Vilém Frynta
Vilém Frynta 2023-2-6
This looks like homework.
It seems like you know what kind of functions you should work with. I'd recommend to study the documention of these functions and try to think it out. Feel free to share your progress.
If you are beginning with Matlab, it's good idea just to try (and learn from mistakes and experiments).

类别

在 Help Center 和 File Exchange 中查找有关 Fourier Analysis and Filtering 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by