Is it possible to concatenate sub-structures within structures into single variables?

I am working with multiple structures that contain several sub-structures, each containing numerous fields. The sub-structures and fields all share the same naming convention for each of the separate "top-level" structures. For example;

Struct1.A.B.data = [5000 x 1 single];

Struct2.A.B.data = [3000 x 1 single];

I'd like to append the variables for each of the subsequent structures into the first one without creating additional structures. For example, after appending all of the additional data, structure 1 would become;

Struct1.A.B.data = [8000 x 1 single] instead of Struct1.A.B.data = [2 x 1 struct]

I'm currently doing this manually by concatenating each field individually and it works but requires many lines of code for large structures, see below.

Struct1.A.B.data = [Struct1.A.B.data Struct2.A.B.data];

This repeats for sub-structures A through Z and sub-structures B through Z, which is very tedious.

Is there a better way of acheiving this?

Side note, I tried using the method described in the question below but this creates the additional structures mentioned above instead of adding the data directly to the variables.

https://uk.mathworks.com/matlabcentral/answers/365191-is-it-possible-to-concatenate-structures-with-the-same-fields-in-to-one-super-structure

Answer 1

[Matt J]

A double nested loop could be used, e.g.,

for A=string(fieldnames(Struct1))'
    
    for B=string(fieldnames(Struct1.(A)))'
    
     Struct1.(A).(B).data = [Struct1.(A).(B).data Struct2.(A).(B).data];
    
    end
    
end

[Jack Smith]

Hi Matt,

The method is clear but I'm getting an error after implementing your code, see below.

"Dot indexing is not supported for variables of this type."

I believe this is because the inner for loop does not return a value for B, see error message below when running the inner loop code in the command window.

B=string(fieldnames(Struct1.(A)))'

Dynamic field or property name must be a string scalar or character

vector.

Any ideas on what is causing this error?

[Matt J]

"Dot indexing is not supported for variables of this type."...Any ideas on what is causing this error?

Yes, but there is no reason to be guessing. You should trap the error with dbstop and see exactly what the variable type is.

The solution assumes all fields of Struct1 and Struct2 are themselves structs. If that is violated, it would explain the error.

[Jack Smith]

I forgot that the sub-structures A and B contained some variables that were not structures, such as strings. I've added an if statement to the inner loop to skip these cases which has fixed the problem.

Thanks for all your help.