清空筛选条件
清空筛选条件

What determines the shape of a logically indexed array?

4 次查看（过去 30 天）
Ondrej Budac
Ondrej Budac 2014-4-3
回答： Ondrej Budac 2014-4-7
Matlab help explains: " Logical Indexing : ... The output is always in the form of a column vector."
In practice, typing
a = ones(3,3);
b = a([true, true]);
gives a row vector b. Can someone tell me why does it behave this way? And is there any other instance (apart from indexing by one row logical vector) that gives a non-column result? Thanks, O.

请先登录，再回答此问题。

采纳的回答

Ondrej Budac
Ondrej Budac 2014-4-7
Just to complete the story, the answer seems to be:
If B is a logical array and A is any array, then A(B) is equivalent (but faster) way to produce the same result as A(find(B)), including the shape of the output.

更多回答（1 个）

Azzi Abdelmalek
Azzi Abdelmalek 2014-4-3
Maybe you need
a = ones(3,3);
b = a([true, true],:)
  7 个评论
显示 5更早的评论
Azzi Abdelmalek
Azzi Abdelmalek 2014-4-3
Just one question, what are you expecting with a(logical([1 0;1 1])) ? The result contains 3 elements
Ondrej Budac
Ondrej Budac 2014-4-3
If I now understand logical indexing correctly, I expect a(logical([1 0;1 1])) to give a column vector with values 1, 4, 2, assuming your definition of a.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Matrices and Arrays 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by