Indexing structure array. Every first entry of an vector.
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Hello, I have stored a lot of vectors in the fields of an structure array and i want to get every first element. s is an 1xN struct. field1 contains the vector
a = s(1:end).field1(1)
or
a = s.field1(1)
give the same error "Expected one output from a curly brace or dot indexing expression, but there were N results."
1 个评论
Stephen23
2018-10-25
"Expected one output from a curly brace or dot indexing expression, but there were N results."
Because you are generating a comma-separated list:
采纳的回答
Bruno Luong
2018-10-25
编辑：Bruno Luong
2018-10-25
If speed is matters, use for-loop
s = struct('field1',num2cell(rand(1,100000)));
tic
a = arrayfun(@(S) S.field1(1), s);
toc % Elapsed time is 0.598622 seconds.
tic
a = zeros(size(s));
for k=1:length(a)
a(k) = s(k).field1(1);
end
toc % Elapsed time is 0.051761 seconds.
2 个评论
Alexander Höll
2018-10-25
Walter Roberson
2018-10-25
You can use hidden for loops such as arrayfun or cellfun, but there is no built-in operation for this situation.
更多回答（1 个）
Walter Roberson
2018-10-25
arrayfun(@(S) S.field1(1), s)
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