Find string between two substrings

Question

How do I find a string between two substrings   123STRINGabc  - gt   STRING     My current method is like this    gt  gt  gt  start    asdf 5    gt  gt  gt  end    123jasd   gt  gt  gt  s    asdf 5 iwantthis123jasd   gt  gt  gt  print  s split start   1  split end  0   iwantthis   However  this seems very inefficient and un-pythonic  What is a better way to do something like this   Forgot to mention  The string might not start and end with start and end  They may have more characters before and after

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Here is one way to do it      rest   s partition start  result       rest partition end  print result   Another way using regexp  import re print re findall re escape start         re escape end  s  0    or  print re search re escape start         re escape end  s  group 1

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To extract STRING  try   myString    123STRINGabc  startString    123  endString    abc   mySubString myString myString find startString  len startString  myString find endString

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start    asdf 5   end    123jasd  s    asdf 5 iwantthis123jasd  print s s find start  len start  s rfind end     gives   iwantthis

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Here is a function I did to return a list with a string s  inbetween string1 and string2 searched   def GetListOfSubstrings stringSubject string1 string2       MyList          intstart 0     strlength len stringSubject      continueloop   1      while intstart  lt  strlength and continueloop    1           intindex1 stringSubject find string1 intstart          if intindex1    -1    The substring was found  lets proceed             intindex1   intindex1 len string1              intindex2   stringSubject find string2 intindex1              if intindex2    -1                   subsequence stringSubject intindex1 intindex2                  MyList append subsequence                  intstart intindex2 len string2              else                  continueloop 0         else              continueloop 0     return MyList    Usage Example mystring  s123y123o123pp123y6  List   GetListOfSubstrings mystring  1   y68   for x in range 0  len List                   print List x   output    mystring  s123y123o123pp123y6  List   GetListOfSubstrings mystring  1   3   for x in range 0  len List                  print List x   output      2     2     2     2  mystring  s123y123o123pp123y6  List   GetListOfSubstrings mystring  1   y   for x in range 0  len List                   print List x   output  23 23o123pp123

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Parsing text with delimiters from different email platforms posed a larger-sized version of this problem   They generally have a START and a STOP  Delimiter characters for wildcards kept choking regex   The problem with split is mentioned here  amp  elsewhere - oops  delimiter character gone  It occurred to me to use replace   to give split   something else to consume   Chunk of code   nuke         start        stop        julien    textIn replace start nuke   start  replace stop stop   nuke  split nuke   keep    chunk for chunk in julien if start in chunk and stop in chunk  logging info  keep   s  keep

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import re  s    asdf 5 iwantthis123jasd  result   re search  asdf 5     123jasd   s  print result group 1

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This I posted before as code snippet in Daniweb     picking up piece of string between separators   function using partition  like partition  but drops the separators def between left right s       before   a   s partition left      a   after   a partition right      return before a after  s    bla bla blaa  lt a gt data lt  a gt  lsdjfasdj  f  important notice   Daniweb forum  tcha tcha tchaa  print between   lt a gt     lt  a gt   s  print between         s  print between         s       Output    bla bla blaa     data     lsdjfasdj xc3 xb6f  important notice   Daniweb forum  tcha tcha tchaa     bla bla blaa  lt a gt data lt  a gt  lsdjfasdj xc3 xb6f     important notice      Daniweb forum  tcha tcha tchaa     bla bla blaa  lt a gt data lt  a gt  lsdjfasdj xc3 xb6f  important notice      Daniweb forum     tcha tcha tchaa

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String formatting adds some flexibility to what Nikolaus Gradwohl suggested  start and end can now be amended as desired   import re  s    asdf 5 iwantthis123jasd  start    asdf 5   end    123jasd   result   re search   s     s     start  end   s  group 1  print result

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Just converting the OP s own solution into an answer   def find between s  start  end     return  s split start   1  split end  0

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If you don t want to import anything  try the string method  index    text    I want to find a string between two substrings  left    find a   right    between two     Output   string  print text text index left  len left  text index right

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s    123123STRINGabcabc   def find between  s  first  last        try          start   s index  first     len  first           end   s index  last  start           return s start end      except ValueError          return     def find between r  s  first  last        try          start   s rindex  first     len  first           end   s rindex  last  start           return s start end      except ValueError          return      print find between  s   123    abc    print find between r  s   123    abc      gives   123STRING STRINGabc   I thought it should be noted - depending on what behavior you need  you can mix index and rindex calls or go with one of the above versions  it s equivalent of regex      and       groups

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s len start  -len end

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This is essentially cji s answer -  Jul 30  10 at 5 58  I changed the try except structure for a little more clarity on what was causing the exception   def find between  inputStr  firstSubstr  lastSubstr        find between firstSubstr and lastSubstr in inputStr  STARTING FROM THE LEFT     http   stackoverflow com questions 3368969 find-string-between-two-substrings         above also has a func that does this FROM THE RIGHT        start  end    -1 -1  try      start   inputStr index  firstSubstr     len  firstSubstr   except ValueError      print      ValueError         print  firstSubstr  s  -      firstSubstr         print sys exc info   1   try      end   inputStr index  lastSubstr  start          except ValueError      print      ValueError         print  lastSubstr  s  -      lastSubstr         print sys exc info   1   return inputStr start end

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These solutions assume the start string and final string are different  Here is a solution I use for an entire file when the initial and final indicators are the same  assuming the entire file is read using readlines     def extractstring line flag           if flag in line      is the flag         dex1 line index flag          subline line dex1 1 -1   leave out flag   1  to end of line         dex2 subline index flag          string subline 0 dex2  strip    does not include last flag  strip whitespace     return string    Example   lines   asdf 1qr3 qtqay 45q at  A NEWT   asdfa afeasd        afafoaltat  I GOT BETTER   derpity derp derp   for line in lines      string extractstring line flag          print string    Gives   A NEWT  I GOT BETTER

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You can simply use this code or copy the function below  All neatly in one line   def substring whole  sub1  sub2       return whole whole index sub1    whole index sub2     If you run the function as follows   print substring  5  5 2  2                You will pobably be left with the output    5 2   rather than  5 2   If you want to have the sub-strings on the end of the output the code must look like below   return whole whole index sub1    whole index sub2    1    But if you don t want the substrings on the end the  1 must be on the first value   return whole whole index sub1    1   whole index sub2

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source  your token  here0 df and maybe  here1 df or maybe  here2 df  start sep     end sep   df  result    tmp source split start sep  for par in tmp    if end sep in par      result append par split end sep  0    print result   must show  here0  here1  here2  the regex is better but it will require additional lib an you may want to go for python only

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My method will be to do something like   find index of start string in s   gt  i find index of end string in s   gt  j  substring   substring i len start  to j-1

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Further from Nikolaus Gradwohl answer  I needed to get version number  i e   0 0 2  between  ui   and  -   from below file content  filename  docker-compose yml        version   3 1  services    ui      image  repo-pkg dev io 21 website ui 0 0 2-QA1      network mode  host     ports        - 443 9999     ulimits        nofile test   and this is how it worked for me  python script    import re  sys  f   open  docker-compose yml    r   lines   f read   result   re search  ui     -   lines  print result group 1    Result  0 0 2

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This seems much more straight forward to me   import re  s    asdf 5 iwantthis123jasd  x  re search  iwantthis  s  print s x start   x end

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from timeit import timeit from re import search  DOTALL   def partition find string  start  end       return string partition start  2  rpartition end  0    def re find string  start  end         applying re escape to start and end would be safer     return search start            end  string  DOTALL  group 1    def index find string  start  end       return string string find start    len start  string rfind end       The wikitext of  Alan Turing law  article form English Wikipeida   https   en wikipedia org w index php title Alan Turing law amp action edit amp oldid 763725886 string             start      Proposals    end      Rival bills     assert index find string  start  end              partition find string  start  end              re find string  start  end   print  index find   timeit       index find string  start  end        globals globals        number 100 000      print  partition find   timeit       partition find string  start  end        globals globals        number 100 000      print  re find   timeit       re find string  start  end        globals globals        number 100 000       Result   index find 0 35047444528454114 partition find 0 5327825636197754 re find 7 552149639286381   re find was almost 20 times slower than index find in this example

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