How to collect data into a vector from this data structure?

I have A.B(i,j).C(k).D(n).E.F, and i,j,k are fixed, but n runs from 1 to N. How to collect data into a vector? I know that it is possible to write a for cycle to do this, but are there any simpler solution in one line to do this? A.B(i,j).C(k).D(:).E.F not works for example.

Answer 1

[Cam Salzberger]

You can make use of the ability to output a comma-separated list of values from a single-level structure array. In other words, if you make a structure array like so:

eg = struct('field', {1 2 3})

Then you can do this:

>> eg.field
ans =
     1
ans =
     2
ans =
     3

Which means you can put that together into a vector with square brackets:

>> [eg.field]
ans =
   1     2     3

Now, since you have a nested structure, you just have to take the intermediate step of making a structure array first, then make a numeric array from that structure array.

Example structure:

for n = 1:10
    A.B(1,1).C(1).D(n).E.F = n;
end

Extraction:

S = [A.B(1,1).C(1).D(:).E]; % Structure array
V = [S(:).F]; % Numeric array

You can change out the fixed indices as you need.

-Cam

[Stephen23]

Read about this in the MATLAB documentation:

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