Finding a string in a series of unknown variables

Say I have a list of variables on my workspace that were randomly generated, but each have a substructure with a title:

workspace looks like this:

• a
• b
• c
• d

but if you type a.title you output "Ch1". Each of these also have substructures where my data is located, usually named .values.

I want to write a script that renames my variables based on what the .title string is. I wrote it by doing this

z = who;

for i = 1:length(z)
    if z(i).title == 'Ch1';
        Ch1.values = z(i).values;
    end
end

but encounter a problem becauze z(i) is not the variable, but rather the string of the variable. In other words, I can't do z(i).title because z(i) = 'a' instead of z(i) = a

Thanks for the help, Alex

[Stephen23]

It is worth noting that generating variable names with eval is almost always a bad idea:

http://blogs.mathworks.com/videos/2010/03/08/top-10-matlab-code-practices-that-make-me-cry/

http://matlab.wikia.com/wiki/FAQ#Programming

http://www.mathworks.com/matlabcentral/answers/57445-faq-how-can-i-create-variables-a1-a2-a10-in-a-loop

http://www.mathworks.com/matlabcentral/answers/143-how-do-i-make-a-series-of-variables-a1-a2-a3-a10

etc, etc...

Answer 1

[Chad Greene]

Does this do what you need?

z = who; 

Ch1.values = z.values{strcmp(z.title,'Ch1')};

[Jinn]

Nope, same issue I run into which is that you can't use the substructure of z because z is now a string instead of a structured variable.

I'm starting to think that 'who' is wrong. I need a function that will let me cycle through the variables in the workspace. Can't find a question that's been asked about this so if it's not solved with this thread I will open a new one about that.

Appreciate the help though

Answer 2

[Guillaume]

If I understood correctly, this should work:

for i = 1:numel(z)
  v = eval(z{i});
  if isstruct(v) && all(ismember({'title', 'values'}, fieldnames(v)))
    eval([v.title ' = v.values;']);
    eval(['clear ' z{i}]);
  end
end

[José-Luis]

Using eval is a bad idea and can usually be avoided.

You could alternatively use assignin or evalin.

[Guillaume]

The whole variable structure in the OP is a bad idea, but that's what it is. evalin would be of no benefit unless the code was written in a function. assignin could replace one of the eval, but in this case, there is no alternative for the 2nd eval.

For reference, the first eval could be replaced with:

assignin('base', v.title, v.values);