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How do I use logical indexing on an array made up of structs that contain character fields?

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Ricardo
Ricardo 2013-2-4
I have a structure with two fields, type and specie, both of which contain character strings. I built an array consisting of only these structures, and now I'm trying to use logical indexing to find the elements of a given type. The code is as follows:
A(1).type = 'insect';
A(1).specie = 'fly';
A(2).type = 'insect';
A(2).specie = 'moth';
A(3).type = 'fish';
A(3).specie = 'grouper';
A(4).type = 'fish';
A(4).specie = 'tuna';
[A([A.type] == 'insect').specie]
I'm modifying the solution to this question, but I get an error that says:
Error using ==
Matrix dimensions must agree.
Error in myfile (line 12)
[A([A.type] == 'insect').specie]
I know that comparing strings with == isn't good, so I thought I would use strcmp instead. However, this code:
[A([strcmp(A.type, 'insect')]).specie]
produces an error of
Error using strcmp
Too many input arguments.
Error in myfile (line 12)
[A([strcmp(A.type, 'insect')]).specie]
If I use an anonymous function, I can create an array of structures that meet the criterion, i.e.
hits = A(arrayfun(@(x)strcmp(x.type, 'insect'), A));
but I don't know how to get the fields from those structures into another array without resorting to a loop.
How can I perform this task using the base Matlab only?

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采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2013-2-4
编辑：Azzi Abdelmalek 2013-2-4
x={A.type}
A(strcmp(x, 'insect')).specie

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