MATLAB: Accessing variables in m file without executing it

access-variablesm-file

I have a .m file that will only run as part of a giant program. However, I want to access some variables in it without running this program. Is this possible?

Best Answer

I agree with Stephen, but have a slughtly more pessimistic opinion:

No, it is not possible, at least not in the general case. You could parse the file and recognize some trivial definitions like:

a = 10;

But as soon as it gets more complex, you need a sophisticated parser. Of course you can create such a parser, but this would be a duplicate of Matlab. And even then the code must be interpreted to get all values, e.g. in:

a = 10;
b = a;

It is a good programming practice, to separate the processing, the gui and the data strictly. Instead of storing a bunch of values inside the function, a MAT file is much better, most of all if the data are needed anywhere else also.

Related Solutions

MATLAB: How to extract coefficients from from curve fitting tool

Simply enough. In fact, they ARE stored in the workspace. They are just not returned as separate variables. And that is a good thing. Extracting them is trivial though.

x = rand(10,1);
y = randn(10,1);
g1 = fit(x,y,'power1')
g1 = 
     General model Power1:
     g1(x) = a*x^b
     Coefficients (with 95% confidence bounds):
       a =     -0.1631  (-0.6644, 0.3382)
       b =     -0.4213  (-2.33, 1.487)
g1.a
ans = -0.1631
g1.b
ans = -0.4213

Or, if you wish to extract them as a vector of coefficients, just do

format long g
coeffvalues(g1)
ans = 1×2
        -0.163113290762181        -0.421325379677972
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MATLAB: Assigning data to variable names in a vector during a for loop.

yes this is possible. you could use the command "eval" that comes with matlab. have a look at the documentation.

for your case you would have to change the variables array to have chars inside - i.e.:

vars = {'a', 'b', 'c'}

and in the for loop use

vals = [1 2 3 4]
vars = {'a', 'b', 'c', 'd'}
for i = vals
    eval([vars{i} '=  vals(i)'])
end

also, you might want to have a look at the "genvarname" command of matlab that does exactly what you want in the second part of your question.

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Related Solutions

MATLAB: How to extract coefficients from from curve fitting tool

MATLAB: Assigning data to variable names in a vector during a for loop.

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