how to get struct array field as a vector?

I have a struct array, and a field like data.age and I want to get the ages as a vector v for which I can write for example : v(v>18), because data.age(data.age>18) gives me an error message.

[Stephen23]

Accessing fields of non-scalar structures is covered quite well in the documentation:

http://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

It is also useful to understand comma separated lists:

http://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

Answer 1

[Thorsten]

 age = [data.age];
 agegt18 = age(age>18);

Answer 2

[Walter Roberson]

v = [data.age];
data(v>18)

Or more compactly,

data([data.age]>18)

[Mr M.]

Thanks, and what if the filed contains strings, and I want to select elements for which string equals to a given string? Something like this: data({data.gender}=='male')

[Thorsten]

Use

data(strcmp({data.gender}, 'male'))

Answer 3

[Tin Aye Chit Chit]

Please check the code, that code can't give me the answer I want.

for i = 1:1:n

V=index{i};

for j = 1:1:size(V,2)

S{i,j}.e = nodeArch.node(V(1,j)).energy;

S{i,j}.t = nodeArch.node(V(1,j)).type;

S{i,j}.g = nodeArch.node(V(1,j)).G;

end

end

The S have more column than V. What is wrong in that code?