Select only some Index in matrix

Question

0 个投票

Hi,

I have two variables:

whos var1 var2        
Name                    Size          
var1                  331x666x31
var2                    11x1                      

Where:

var2 = [ 3 5 6 7 8 9 10 11 12 15 16]

I only want to keep this numbers as index in the third dimension of var1. It's correct If I just do the following?

var3 = var1(:,:,var2);

Or a better approach would be use a for loop?

for i1 = 1:size(var2,1)
    dummy = var2(i1);
    var3(:,:,i1) = var1(:,:,dummy);
end

I'm concerned with optimization since I need to do this inside another for loop. Which is better or is there another better approach?

Thank in advance

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Answer 1

Matt J 2022-3-3

编辑：Matt J 2022-3-3

1 个投票

The former approach is definitely better. It uses half as much memory and should be much faster for large var2.

user20912 2022-3-3

Thanks for your fast answer.

Matt J 2022-3-3

You're welcome, but please Accept-click the answer if your question is now resolved.