Read equations from a text file and create a cell array in MATLAB
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Tiasa Ghosh
on 7 May 2018
Answered: Walter Roberson
on 7 May 2018
Hello everybody! I have a text file with 8000 equations and I want to create a cell array of 8000x1 for the equations as strings. I have considered textscan for this purpose, but all the equations doesn't have same number of variables and hence I cannot specify the number of columns. How do I go about it? Example:
equations.txt:
1. a=b+c
2. d=e+f+g+h
3. y=2+x*z
4 Comments
Walter Roberson
on 7 May 2018
Are the line numbers present in the file? If they are do you want them read in or discarded?
Accepted Answer
Walter Roberson
on 7 May 2018
Provided there are no UNICODE or UTF-8 characters in the file:
filename = 'equations.txt';
S = fileread(filename);
equations = regexp(S, '\r?\n', 'split');
if isempty(equations{end}); equations(end) = []; end %last entry is often empty due to the way regexp split works
If the file does include Unicode that is UTF encoded, then potentially more steps would need to be used to read it properly.
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More Answers (1)
Ameer Hamza
on 7 May 2018
Edited: Ameer Hamza
on 7 May 2018
The following lines will read the lines from the text file and return a cell array of function handles
f = fopen('test.txt');
q = textscan(f, '%s');
fclose(f);
funHandles = cell(1, length(q{1}));
for i=1:length(q{1})
splitAtEqualSign = strsplit(q{1}{i}, '=');
rhs = splitAtEqualSign{2};
funHandles{i} = matlabFunction(str2sym(rhs));
end
3 Comments
Ameer Hamza
on 7 May 2018
Edited: Ameer Hamza
on 7 May 2018
Then don't run for loop. q{1} contain cell array of strings.
Ameer Hamza
on 7 May 2018
Since you mentioned that line numbers are not present. I have updated the answer.
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