How do I index an array with varying dimension?
5 views (last 30 days)
Show older comments
runtime_error
on 9 Feb 2024
Commented: Stephen23
on 9 Feb 2024
I have a function Y = func(X)
X can be any dimension >=2. Inside the function, I need to index X by the first dimension. X(index, :) or X(index, :, :) depending on the dimension. I know I can check the dimension like this:
if ndims(X) == 2
X(index, :) = ....
elseif ndims(x) == 3
X(index, :, :) = ..
end
Is there a more efficient way?
Accepted Answer
Walter Roberson
on 9 Feb 2024
If you use a trailing dimension of : to index, then the result has the proper size but with the dimension "unwrapped"
A = ones(3,4,5);
B = A(2,:);
size(B)
You can leave it like that for computations, or you can reshape() it
sz = size(A);
sz(1) = 1;
C = reshape(B,sz);
size(C)
Alternately....
indx = repmat({':'}, 1, ndims(A));
indx{1} = 2;
D = A(indx{:});
size(D)
0 Comments
More Answers (0)
See Also
Categories
Find more on Matrix Indexing in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!