How to slice a struct array?

Question

How can I extract a specific field from each element of a Matlab struct array?

>> clear x
>> x(1).a = 6;
>> x(2).a = 7;

I

Answer 1

For a multi-dimensional array, you need

reshape([x.a], size(x))

Answer 2

If elements of the struct are strings, the accepted solution concatenates all cells. The more general

vertcat(x.a)

works in all cases. Ref

Answer 3

No problem - just use :

arr = [x.a];

It will concat all of the values that you need. If you have a more complex data, you can use the curly bracers:

b(1).x = 'John';
b(2).x = 'Doe';
arr = {b.x}; 

Answer 4

Sadly, I am almost sure that MATLAB has no nice way of doing what you want. You will have to either use a for loop to construct a new array, or else go back and redesign your data structures. For example you might be able to use a struct-of-arrays rather than an array-of-structs.