Regular Expression pattern for matching a variable name after an operator (mathematical or logical) ?
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Hello, i am new to regular expressions and using regexprep as well. I want to write a function which replaces names of variables with a given new name. The expression i used first was (^|\W)oldName(\W|$) and $1newName$2 as the replacement.
Unfourtunatly this will not replace expressions like variableA*variableA or variableB+variableB. The second factor or summand is not replaced so i have to do regexp() twice. Secondly i tried the expression (^*|\W)oldName(\W|$) which will replace the second factor in the example above, but will also replace the name in something like this: thisvariableA.
matchPattern = (^|\W)oldName(\W|$);
replacePattern = $1newName$2;
StringContent = 'oldName*oldName';
ContentNew = regexprep(StringContent , replacePattern , matchPattern);
So i am looking for a regexp pattern which matches 'oldName' also after an operator which follows after and before'oldName'. A way to match the given example would help.
采纳的回答
>> regexprep('variableA*variableA','(?<=\W)\w+','newName')
ans = variableA*newName
>> regexprep('variableB+variableB','(?<=\W)\w+','newName')
ans = variableB+newName
Your specification is quite vague: do you want to replace all of the instances of variableX with newName, or only the one after the operator (as your title states)? To learn how to write regular expressions read this page very carefully, and refer to it all the time:
You might also be interested in downloading my FEX submission iregexp, which provides an interactive tool for experimenting with regular expressions and showing regexp's outputs as you type:
It is useful for quickly experimenting with and refining regular expressions.
7 个评论
Kai Teschner
2018-8-3
>> regexprep('variableA*variableA','\w+','newName')
ans = newName*newName
Fangjun Jiang
2018-8-3
编辑：Fangjun Jiang
2018-8-3
@Stephen Cobeldick, incomplete
>> regexprep('AnyVar*variableA','\w+','newName')
ans =
'newName*newName'
@Kai Teschner: your specification is not very clear, but if you want to replace one specific name anywhere in the original string, as many times as it occurs, then just do this:
>> regexprep('AnyVar*variableA','variableA','newName')
ans = AnyVar*newName
(or the same thing using strrep).
If there is the possibility of conflict, i.e. the variable name might be part of a longer string that you do NOT want to replace, then you can do this (where I want to replace A but not inside the words And or AnyVar):
>> regexprep('A/A And AnyVar*A And A+A','\<A\>','B')
ans = B/B And AnyVar*B And B+B
As you can see there are many options and possibilities. It all depends on your specification, which so far is not precise enough: if you want more help, please make a really clear specification: the more precise you are, the happier you will be with the result!
Note that an alternative might be to use the symbolic math toolbox, which includes variable substitution as a basic operation... this might be a good option, as in general using string manipulations to work with mathematical equations and formulas is not very efficient.
Kai Teschner
2018-8-3
"Yes i want to replace specific names of variables within a .m-file content"
Hopefully you are not doing some kind of meta-programing! You can simply use the MATLAB editor to search-and-replace variable names (it even does this intelligently, only replacing the whole variable name as you want).
"I do not want to replace the name WITHIN another name..."
Did you try the code I gave in my last example? It seems to do exactly what you are asking for:
>> str = 'VariableA*VariableB but not ThisVariableA VariableA+VariableA';
>> rgx = '\<VariableA\>';
>> rpl = 'newName';
>> regexprep(str,rgx,rpl)
ans = newName*VariableB but not ThisVariableA newName+newName
Kai Teschner
2018-8-6
更多回答（1 个）
Sean de Wolski
2018-8-3
编辑：Sean de Wolski
2018-8-3
You may wish to consider using the shift+enter option in the MATLAB editor.
Find where variableA is defined for the first time or anywhere it is on the left of the = sign. E.g:
function(variableA)
or
variableA = something
Put the mouse cursor in it.
Change name by typing.
A yellow dialog will appear saying shift+enter to rename everywhere.
Hit shift+enter
Done.
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