Select only some Index in matrix

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

Answer 1

[Matt J]

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

[user20912]

Thanks for your fast answer.

[Matt J]

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