3D Matrix indexing from a vector

1 次查看（过去 30 天）
Aviv Ofir
Aviv Ofir 2012-11-13
Hi,
If one puts a matrix of indices I to a vector A (e.g,: A(I)) one would get an output with the size of I filled with the values of A in the location given by I. Now, suppose A is now a matrix itself, and I want the above procedure to be applied to each row of A individually, placing each output matrix in a different page of a resultant 3D array.
Here is a sample code that works using a loop:
A=[ 1 2 3 4 5 6 7 8 9 0;... % values
11 12 13 14 15 16 17 18 19 20;...
21 22 23 24 25 26 27 28 29 30;...
31 32 33 34 35 36 37 38 39 40;...
41 42 43 44 45 46 47 48 49 50];
I=[7 8 5 7 9 5 6 7 8 9;... indices
2 3 1 4 3 1 4 2 3 1];
% Build Acube
for i=1:size(A,1)
tmp=A(i,:);
Acube(:,:,i)=tmp(I);
end;
The question is: how can you vectorize it? (I note I used "large" (>=5) values for the first row of I, and "small" values (<5) for the second row to ease debugging - but any value between 1 and size(A,2) should work).

请先登录，再回答此问题。

采纳的回答

Matt J
Matt J 2012-11-13
编辑：Matt J 2012-11-13
[m,n]=size(I);
Acube=reshape(A(:,I).',m,n,[]),

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Matrix Indexing 的更多信息

标签

产品

Community Treasure Hunt

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

Start Hunting!

Translated by