logical indexing for dlarrays

Hello,

I noticed that when I perform logical indexing on a formatted dlarray, it looses its format. Does anyone has an idea why this is and how I could workaround this? I want to do automatic differentiation afterwards, so I guess when the format is removed, that might be not possible.

Any help would be appreciated!

x = dlarray([1, 2, 3], "CB")

x = 
  1(C) × 3(B) dlarray

     1     2     3

index = [true, false, true];
xNew = x(index)

xNew = 
  1×2 dlarray

     1     3

Answer 1

[Prince Kumar]

Hi,

This is the intended behaviour once you index "dlarray".

Possible workaround is to re-apply the format. Here is the way to do it :

x = dlarray([1, 2, 3, 4, 5], "CB");
index = [true, false, true];

xNew = x(index);
xNew = dlarray(xNew, "CB")

xNew = 
  1(C) × 2(B) dlarray

     1     3

dims(xNew)

ans = 'CB'

As you can see now, xNew will have the format as "CB".

Hope this helps.

[Rasmus Joussen]

I just noticed that this was mor a problem of my wrong indexing, since a CB dlarray hast two dimensions I must have to indices:

x = dlarray([1, 2, 3], "CB")

x = 
  1(C) × 3(B) dlarray

     1     2     3

index = [true, false, true];
xNew = x(:, index)

xNew = 
  1(C) × 2(B) dlarray

     1     3

Thank you anyway!