Assess element in struct which filed name contains '.'

hello folks,

I am trying to get the elements from the multiple structs data. for example

a =  data.x1.data(1)

when I try to loop this in for loop, I need to increase the number following by x for example

data.x1.data(1) data.x2.data(1)

so I simply used this

for i = 1:b;
    data0(i,4) =(data.x(i).data(1))
end

but it keeps saying that 'Reference to non-existent field 'x'.'

How can I resolve this error? it doesn't have any problem when I use

data.x1.data(1)

hope anyone of you can guide me :(

thanks, Ali

[Stephen23]

This syntax:

data.x(i)

trieds to access the i-th element of the field x. Your structure data does not contain the field x, so this will not work (unless you improve your data design to use a non-scalar structure).

Answer 1

[Stephen23]

You will need to use a dynamic fieldname:

for k = 1:b;
    fld = sprint('x%d',k);
    data.(fld).data
end

Your code would be simpler and more efficient if you just used a non-scalar structure, then you could just use indexing:

>> S(1).data = 1:3;
>> S(2).data = 4:6;
>> S(3).data = 7:9;
>> for k = 1:3, S(k).data(1), end
ans =  1
ans =  4
ans =  7

Personally I would also recommend avoiding using nested structures, as then you can use the very convenient comma-separated list syntax for handling multiple elements of the structure.

[Areum Lee]

thank you very much for the quick answer. that's what I exactly wanted.