Find index of last occurrence of a substring in a string

Question

I want to find the position  or index  of the last occurrence of a certain substring in given input string str   For example  suppose the input string is str    hello  and the substring is target    l   then it should output 3   How can I do this

User · Answer

you can use rindex   function to get the last occurrence of a character in string  s  hellloooloo  b  l  print s rindex b

User · Answer

Try this   s    hello plombier pantin  print  s find  p    6 print  s index  p    6 print  s rindex  p    15 print  s rfind  p

User · Answer

Use the str rindex method    gt  gt  gt   hello  rindex  l   3  gt  gt  gt   hello  index  l   2

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Not trying to resurrect an inactive post  but since this hasn t been posted yet      This is how I did it before finding this question   s    hello  target    l  last pos   len s  - 1 - s   -1  index target    Explanation  When you re searching for the last occurrence  really you re searching for the first occurrence in the reversed string  Knowing this  I did s   -1   which returns a reversed string   and then indexed the target from there  Then I did len s  - 1 - the index found because we want the index in the unreversed  i e  original  string   Watch out  though  If target is more than one character  you probably won t find it in the reversed string  To fix this  use last pos   len s  - 1 - s   -1  index target   -1    which searches for a reversed version of target

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If you don t wanna use rfind then this will do the trick   def find last s  t       last pos   -1     while True          pos   s find t  last pos   1          if pos    -1              return last pos         else              last pos   pos

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The more itertools library offers tools for finding indices of all characters or all substrings   Given  import more itertools as mit   s    hello  pred   lambda x  x     l    Code  Characters  Now there is the rlocate tool available   next mit rlocate s  pred     3   A complementary tool is locate   list mit locate s  pred   -1    3  mit last mit locate s  pred     3     Substrings  There is also a window size parameter available for locating the leading item of several items   s    How much wood would a woodchuck chuck if a woodchuck could chuck wood   substring    chuck  pred   lambda  args  args    tuple substring   next mit rlocate s  pred pred  window size len substring      59

User · Answer

Use  rfind      gt  gt  gt  s    hello   gt  gt  gt  s rfind  l   3   Also don t use str as variable name or you ll shadow the built-in str

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Python String rindex   Method  Description Python string method rindex   returns the last index where the substring str is found  or raises an exception if no such index exists  optionally restricting the search to string beg end    Syntax  Following is the syntax for rindex   method -  str rindex str  beg 0 end len string     Parameters str - This specifies the string to be searched   beg - This is the starting index  by default its 0  len - This is ending index  by default its equal to the length of the string   Return Value This method returns last index if found otherwise raises an exception if str is not found   Example The following example shows the usage of rindex   method   Live Demo    usr bin python  str1    this is string example    wow      str2    is    print str1 rindex str2  print str1 index str2    When we run above program  it produces following result -  5 2   Ref  Python String rindex   Method - Tutorialspoint

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You can use rfind   or rindex    Python2 links  rfind    rindex     gt  gt  gt  s    Hello StackOverflow Hi everybody    gt  gt  gt  print  s rfind  H     20   gt  gt  gt  print  s rindex  H     20   gt  gt  gt  print  s rfind  other     -1   gt  gt  gt  print  s rindex  other     Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt  ValueError  substring not found   The difference is  when the substring is not found  rfind   returns -1 while rindex   raises an exception ValueError  Python2 link  ValueError    If you do not want to check the rfind   return code -1  you may prefer rindex   that will provide an understandable error message  Else you may search for minutes where the unexpected value -1 is coming from within your code       Example  Search of last newline character   gt  gt  gt  txt      first line     second line     third line      gt  gt  gt  txt rfind   n   22   gt  gt  gt  txt rindex   n   22

[python] Find index of last occurrence of a substring in a string

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