Substitute string to double

Hi everyone, very simple question here:

I have this:

Acell =

  3×3 cell array

    '0+1/R1'    '0-1/R1'         '1'
    '0-1/R1'    '0+1/R1+1/R2'    '0'
    '1'         '0'              '0'

Apart from that, I have this:

R1 = '1000'; 
R2 = '1000'; 

My goal is to convert the original string to a double array so I could perform calculations afterwards, like this:

A = [ 1/1000 -1/1000 1; -1/1000 1/1000+1/1000 0; 1 0 0;];

What I tried so far was:

Acell = strrep(Acell,'R1','1000');
Acell = strrep(Acell,'R2','1000');
A = str2double(Acell);

Obtaining:

A =

   NaN   NaN     1
   NaN   NaN     0
     1     0     0

Any thoughts? This is just a little example, my idea is doing that job for much more elements so I'm not sure about using 'strrep' too.

Many thanks in advance

Answer 1

[Stephen23]

>> A = {'0+1/R1','0-1/R1','1';'0-1/R1','0+1/R1+1/R2','0';'1','0','0'};
>> A = strrep(A,'R1','1000');
>> A = strrep(A,'R2','1000');
>> B = cellfun(@str2num,A)
B =
    0.0010   -0.0010    1.0000
   -0.0010    0.0020         0
    1.0000         0         0

Warning: will run arbitrary commands, use at your own risk!

Rather than storing functions as strings, perhaps they should be stored as function handles. Then you can simply and effiiciently call them with the required input data (as numeric, of course!).

>> A = {'0+1/R1','0-1/R1','1';'0-1/R1','0+1/R1+1/R2','0';'1','0','0'};
>> F = cellfun(@(s)str2func(['@(R1,R2)',s,';']),A,'uni',0); % convert to function handle
>> B = cellfun(@(f)f(1000,1000),F) % call all with the same inputs
B =
    0.0010   -0.0010    1.0000
   -0.0010    0.0020         0
    1.0000         0         0
>> F{1,2}(20,30) % call function {1,2}
ans =
   -0.0500

[Juan Castillo]

Thank you very much!!

Answer 2

[madhan ravi]

Requires Symbolic Math Toolbox:

Wanted = str2sym(regexprep(Acell, {'R1', 'R2'}, {R1, R2}))
%or for older versions
Wanted = sym(regexprep(Acell, {'R1', 'R2'}, {R1, R2})) % not tested

[Juan Castillo]

Hi, thanks for your answer, but still get an error doing whatever you said:

Error using regexprep
All cells must be char row vectors.

[madhan ravi]

Works in 2020a just fine.