logical indexing for dlarrays

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Rasmus Joussen
Rasmus Joussen 2022-1-17
评论： Rasmus Joussen 2022-1-20
Ran in:
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

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回答（1 个）

Prince Kumar
Prince Kumar 2022-1-20
编辑：Prince Kumar 2022-1-20
Ran in:
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.
  1 个评论
Rasmus Joussen
Rasmus Joussen 2022-1-20
Ran in:
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!

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