Substitute string to double
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Juan Castillo
on 17 Sep 2020
Commented: Juan Castillo
on 20 Sep 2020
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
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Accepted Answer
Stephen23
on 18 Sep 2020
Edited: Stephen23
on 18 Sep 2020
>> 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
More Answers (1)
madhan ravi
on 17 Sep 2020
Edited: madhan ravi
on 17 Sep 2020
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
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