How do you elegantly load dynamic variables into a cell array?

I have a chain on outputs coming out of Simulink. The order of the outputs matter, hence the numbering.

When working with it in MATLAB, I would much prefer to reference this data as A{1}, A{2}, ect, so I can expand my system seamlessly. I tried setting the To Workspace blocks to A{1}, A{2}, ect in Simulink but it didn't like that. So I've been attempting to use arrayfun + eval in MATLAB to feed these variables into a single cell array. Eval returns the value I expect but it won't feed it into arrayfun.

% dummy data for demo purposes
out.A1.Data = [1 1 1]; out.A2.Data = [2 2 2]; out.A3.Data = [3 3 3];

% eval - WORKS
eval(sprintf("out.A%0.0f.Data",1))

ans = 1×3

1 1 1

nodes = 1:3;
% loop - WORKS
for k = nodes
    A{k} = eval(sprintf("out.A%0.0f.Data",k));
end
A

A = 1×3 cell array
    {[1 1 1]}    {[2 2 2]}    {[3 3 3]}

% arrayfun - FAILS
arrayfun(@(x) eval(sprintf("out.A%0.0f.Data",x)),nodes,"UniformOutput",false)

Unable to resolve the name out.A1.Data.

Error in solution (line 13)
arrayfun(@(x) eval(sprintf("out.A%0.0f.Data",x)),nodes,"UniformOutput",false)

What am I missing? I know I can do this in a loop, but I feel like there is a sleeker solution. The whole point of arrayfun is to condense one line loops, which is exsactly what I'm calling.

Answer 1

[Jan]

Avoid eval. Instead of

eval(sprintf("out.%s.Data","A1"))

this is faster, safer and nicer:

out.('A1').Data

Then the loop becomes:

for k = 1:3
    A{k} = out.(sprintf('A%d', k)).Data;
end

If you want to do this without a loop (although this is slower):

out.A1.Data = [1 1 1]; out.A2.Data = [2 2 2]; out.A3.Data = [3 3 3];
A = cellfun(@(x) x.Data, struct2cell(out), 'UniformOutput', false)

[Sydney Lang]

I had no idea you could index with ('') notation, thats so useful! Thank you, I'll defiently use the fast version.

[Stephen23]

https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html