Python re.finditer error at special characters












1














I have code that loops through a list of strings, then loops through each occurrence of that string inside another string. This seems to work until it reaches a string that begins with a question mark (? I).



This is the code.



dtID = 0
for datum in sorted(datumList, key=operator.attrgetter('Sum'), reverse = True):
datum.ID = dtID
for foundDatum in re.finditer(datum.Name, text):
datumLocList.append(DatumLoc(dtID,foundDatum.start()))
dtID += 1


How can I solve this?



Traceback (most recent call last):
File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 97, in <module>
compress()
File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 73, in compress
for foundDatum in re.finditer(datum.Name, text):
File "C:Program FilesPython37libre.py", line 230, in finditer
return _compile(pattern, flags).finditer(string)
File "C:Program FilesPython37libre.py", line 286, in _compile
p = sre_compile.compile(pattern, flags)
File "C:Program FilesPython37libsre_compile.py", line 764, in compile
p = sre_parse.parse(p, flags)
File "C:Program FilesPython37libsre_parse.py", line 930, in parse
p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
File "C:Program FilesPython37libsre_parse.py", line 426, in _parse_sub
not nested and not items))
File "C:Program FilesPython37libsre_parse.py", line 651, in _parse
source.tell() - here + len(this))
re.error: nothing to repeat at position 0









share|improve this question



























    1














    I have code that loops through a list of strings, then loops through each occurrence of that string inside another string. This seems to work until it reaches a string that begins with a question mark (? I).



    This is the code.



    dtID = 0
    for datum in sorted(datumList, key=operator.attrgetter('Sum'), reverse = True):
    datum.ID = dtID
    for foundDatum in re.finditer(datum.Name, text):
    datumLocList.append(DatumLoc(dtID,foundDatum.start()))
    dtID += 1


    How can I solve this?



    Traceback (most recent call last):
    File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 97, in <module>
    compress()
    File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 73, in compress
    for foundDatum in re.finditer(datum.Name, text):
    File "C:Program FilesPython37libre.py", line 230, in finditer
    return _compile(pattern, flags).finditer(string)
    File "C:Program FilesPython37libre.py", line 286, in _compile
    p = sre_compile.compile(pattern, flags)
    File "C:Program FilesPython37libsre_compile.py", line 764, in compile
    p = sre_parse.parse(p, flags)
    File "C:Program FilesPython37libsre_parse.py", line 930, in parse
    p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
    File "C:Program FilesPython37libsre_parse.py", line 426, in _parse_sub
    not nested and not items))
    File "C:Program FilesPython37libsre_parse.py", line 651, in _parse
    source.tell() - here + len(this))
    re.error: nothing to repeat at position 0









    share|improve this question

























      1












      1








      1







      I have code that loops through a list of strings, then loops through each occurrence of that string inside another string. This seems to work until it reaches a string that begins with a question mark (? I).



      This is the code.



      dtID = 0
      for datum in sorted(datumList, key=operator.attrgetter('Sum'), reverse = True):
      datum.ID = dtID
      for foundDatum in re.finditer(datum.Name, text):
      datumLocList.append(DatumLoc(dtID,foundDatum.start()))
      dtID += 1


      How can I solve this?



      Traceback (most recent call last):
      File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 97, in <module>
      compress()
      File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 73, in compress
      for foundDatum in re.finditer(datum.Name, text):
      File "C:Program FilesPython37libre.py", line 230, in finditer
      return _compile(pattern, flags).finditer(string)
      File "C:Program FilesPython37libre.py", line 286, in _compile
      p = sre_compile.compile(pattern, flags)
      File "C:Program FilesPython37libsre_compile.py", line 764, in compile
      p = sre_parse.parse(p, flags)
      File "C:Program FilesPython37libsre_parse.py", line 930, in parse
      p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
      File "C:Program FilesPython37libsre_parse.py", line 426, in _parse_sub
      not nested and not items))
      File "C:Program FilesPython37libsre_parse.py", line 651, in _parse
      source.tell() - here + len(this))
      re.error: nothing to repeat at position 0









      share|improve this question













      I have code that loops through a list of strings, then loops through each occurrence of that string inside another string. This seems to work until it reaches a string that begins with a question mark (? I).



      This is the code.



      dtID = 0
      for datum in sorted(datumList, key=operator.attrgetter('Sum'), reverse = True):
      datum.ID = dtID
      for foundDatum in re.finditer(datum.Name, text):
      datumLocList.append(DatumLoc(dtID,foundDatum.start()))
      dtID += 1


      How can I solve this?



      Traceback (most recent call last):
      File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 97, in <module>
      compress()
      File "C:UserstristDocumentsPythonThe CompressorThe Compressor.py", line 73, in compress
      for foundDatum in re.finditer(datum.Name, text):
      File "C:Program FilesPython37libre.py", line 230, in finditer
      return _compile(pattern, flags).finditer(string)
      File "C:Program FilesPython37libre.py", line 286, in _compile
      p = sre_compile.compile(pattern, flags)
      File "C:Program FilesPython37libsre_compile.py", line 764, in compile
      p = sre_parse.parse(p, flags)
      File "C:Program FilesPython37libsre_parse.py", line 930, in parse
      p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
      File "C:Program FilesPython37libsre_parse.py", line 426, in _parse_sub
      not nested and not items))
      File "C:Program FilesPython37libsre_parse.py", line 651, in _parse
      source.tell() - here + len(this))
      re.error: nothing to repeat at position 0






      python-3.x






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 23 '18 at 11:42









      Tristan KingTristan King

      659




      659
























          1 Answer
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          1














          Your pattern string containing a question mark is being treated as a regular expression special character. The ? symbol attempts to match 0 or 1 repetitions of the preceding regular expression. Since in your string the ? is the first character, it is attempting to match 0 or 1 repetitions of the preceding regular expression, which is nothing: hence your 'nothing to repeat at position 0' error.



          To avoid this you can use the re.escape() method which will escape all RE special characters in your pattern string.



          for foundDatum in re.finditer(re.escape(datum.Name), text):
          datumLocList.append(DatumLoc(dtID,foundDatum.start()))


          See https://docs.python.org/3/library/re.html#re.escape






          share|improve this answer





















          • Works great, thanks.
            – Tristan King
            Nov 23 '18 at 12:51











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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1














          Your pattern string containing a question mark is being treated as a regular expression special character. The ? symbol attempts to match 0 or 1 repetitions of the preceding regular expression. Since in your string the ? is the first character, it is attempting to match 0 or 1 repetitions of the preceding regular expression, which is nothing: hence your 'nothing to repeat at position 0' error.



          To avoid this you can use the re.escape() method which will escape all RE special characters in your pattern string.



          for foundDatum in re.finditer(re.escape(datum.Name), text):
          datumLocList.append(DatumLoc(dtID,foundDatum.start()))


          See https://docs.python.org/3/library/re.html#re.escape






          share|improve this answer





















          • Works great, thanks.
            – Tristan King
            Nov 23 '18 at 12:51
















          1














          Your pattern string containing a question mark is being treated as a regular expression special character. The ? symbol attempts to match 0 or 1 repetitions of the preceding regular expression. Since in your string the ? is the first character, it is attempting to match 0 or 1 repetitions of the preceding regular expression, which is nothing: hence your 'nothing to repeat at position 0' error.



          To avoid this you can use the re.escape() method which will escape all RE special characters in your pattern string.



          for foundDatum in re.finditer(re.escape(datum.Name), text):
          datumLocList.append(DatumLoc(dtID,foundDatum.start()))


          See https://docs.python.org/3/library/re.html#re.escape






          share|improve this answer





















          • Works great, thanks.
            – Tristan King
            Nov 23 '18 at 12:51














          1












          1








          1






          Your pattern string containing a question mark is being treated as a regular expression special character. The ? symbol attempts to match 0 or 1 repetitions of the preceding regular expression. Since in your string the ? is the first character, it is attempting to match 0 or 1 repetitions of the preceding regular expression, which is nothing: hence your 'nothing to repeat at position 0' error.



          To avoid this you can use the re.escape() method which will escape all RE special characters in your pattern string.



          for foundDatum in re.finditer(re.escape(datum.Name), text):
          datumLocList.append(DatumLoc(dtID,foundDatum.start()))


          See https://docs.python.org/3/library/re.html#re.escape






          share|improve this answer












          Your pattern string containing a question mark is being treated as a regular expression special character. The ? symbol attempts to match 0 or 1 repetitions of the preceding regular expression. Since in your string the ? is the first character, it is attempting to match 0 or 1 repetitions of the preceding regular expression, which is nothing: hence your 'nothing to repeat at position 0' error.



          To avoid this you can use the re.escape() method which will escape all RE special characters in your pattern string.



          for foundDatum in re.finditer(re.escape(datum.Name), text):
          datumLocList.append(DatumLoc(dtID,foundDatum.start()))


          See https://docs.python.org/3/library/re.html#re.escape







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 23 '18 at 12:04









          Robbie DunnRobbie Dunn

          864




          864












          • Works great, thanks.
            – Tristan King
            Nov 23 '18 at 12:51


















          • Works great, thanks.
            – Tristan King
            Nov 23 '18 at 12:51
















          Works great, thanks.
          – Tristan King
          Nov 23 '18 at 12:51




          Works great, thanks.
          – Tristan King
          Nov 23 '18 at 12:51


















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