replacing all occurrences of a string in a file using regexp

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Robert Jones 2022-11-10

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评论： Robert Jones 2022-11-14

采纳的回答： Jan

Hello,

I have a very large file that contains sections like these below

VariableProp('GND_R', 'UD', '', '130mm')

VariableProp('T', 'UD', '', '1mm')

VariableProp('RC', 'UD', '', '38mm')

VariableProp('ALFAD', 'UD', '', '255deg')

I need to find all the occurrences of VariableProp(VarName, 'UD', '', VarValue) in the file, and change the VarValue

I am still learning the regexp topic, so in this case help would be appreciated

Thank you

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Chris 2022-11-11

I've found https://regexr.com/ to be a useful resource for figuring out regular expressions (though there may be some minor disagreement with regexp(), not sure), but Jan's prototype is more Matlabby, easier to understand, and perhaps more performant.

Rik 2022-11-11

You are not giving many details.

What are the requirements for those names? Can any characters occurs between those quotes? If that includes single quotes, how are those escaped?

You say you want to change the VarValue part, but you haven't given any indication of what kind of change you want to make.

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采纳的回答

Jan 2022-11-11

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https://ww2.mathworks.cn/matlabcentral/answers/1848243-replacing-all-occurrences-of-a-string-in-a-file-using-regexp#answer_1097103

编辑：Jan 2022-11-11

在 MATLAB Online 中打开

Is it required to use regexp? If not:

C = readlines(FileName);
m = startsWith(C, "VariableProp('" + VarName + ", 'UD', '', ");
C(m) = sprintf("VariableProp('%s', 'UD', '', '%g%s')", VarName, newValue, newUnit);
writelines(FileName, C);

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Jan 2022-11-11

在 MATLAB Online 中打开

@Robert Jones: I guess you have these input data beside the file:

newData = {'GND_R', '130mm'; ...
           'T', '1mm'; ...
           'RC', '38mm'};

If you post the format of your input, a better matching suggestion could be given.

Then you can expand my code:

C = readlines(FileName);
for k = 1:height(newData)
   VarName = newData{k, 1};
   Value   = newData{k, 2};
   m    = startsWith(C, "VariableProp('" + VarName + ", 'UD', '', ");
   C(m) = sprintf("VariableProp('%s', 'UD', '', '%s')", VarName, Value);
end
writelines(FileName, C);