How would I get everything before a in a string Python

Question

I am looking for a way to get all of the letters in a string before a   but I have no idea on where to start  Would I use regex  If so how   string    Username  How are you today     Can someone show me a example on what I could do

User · Answer

You don t need regex for this   gt  gt  gt  s    Username  How are you today     You can use the split method to split the string on the     character   gt  gt  gt  s split        Username     How are you today      And slice out element  0  to get the first part of the string   gt  gt  gt  s split      0   Username

User · Answer

partition   may be better then split   for this purpose as it has the better predicable results for situations you have no delimiter or more delimiters

User · Answer

I have benchmarked these various technics under Python 3 7 0  IPython   TLDR  fastest  when the split symbol c is known   pre-compiled regex  fastest  otherwise   s partition c  0   safe  i e   when c may not be in s   partition  split  unsafe  index  regex   Code import string  random  re  SYMBOLS   string ascii uppercase   string digits SIZE   100  def create test set string length       for   in range SIZE           random string      join random choices SYMBOLS  k string length           yield  random choice random string   random string   for string length in  2  4  2  8  2  16  2  32       print  quot  nString length  quot   string length      print  quot   regex  compiled   quot   end  quot   quot       test set for regex     re compile  quot       quot    c  match  s  for  c  s  in test set       timeit  re match s  group   for  re match  s  in test set for regex      test set   list create test set 16       print  quot   partition         quot   end  quot   quot        timeit  s partition c  0  for  c  s  in test set      print  quot   index             quot   end  quot   quot        timeit  s  s index c   for  c  s  in test set      print  quot   split  limited    quot   end  quot   quot        timeit  s split c  1  0  for  c  s  in test set      print  quot   split             quot   end  quot   quot        timeit  s split c  0  for  c  s  in test set      print  quot   regex             quot   end  quot   quot        timeit  re match  quot       quot    c  s  group   for  c  s  in test set   Results String length  16   regex  compiled   156 ns    4 41 ns per loop  mean    std  dev  of 7 runs  10000000 loops each    partition         19 3   s    430 ns per loop  mean    std  dev  of 7 runs  100000 loops each    index             26 1   s    341 ns per loop  mean    std  dev  of 7 runs  10000 loops each    split  limited    26 8   s    1 26   s per loop  mean    std  dev  of 7 runs  10000 loops each    split             26 3   s    835 ns per loop  mean    std  dev  of 7 runs  10000 loops each    regex             128   s    4 02   s per loop  mean    std  dev  of 7 runs  10000 loops each   String length  256   regex  compiled   167 ns    2 7 ns per loop  mean    std  dev  of 7 runs  10000000 loops each    partition         20 9   s    694 ns per loop  mean    std  dev  of 7 runs  10000 loops each    index             28 6   s    2 73   s per loop  mean    std  dev  of 7 runs  10000 loops each    split  limited    27 4   s    979 ns per loop  mean    std  dev  of 7 runs  10000 loops each    split             31 5   s    4 86   s per loop  mean    std  dev  of 7 runs  10000 loops each    regex             148   s    7 05   s per loop  mean    std  dev  of 7 runs  1000 loops each   String length  65536   regex  compiled   173 ns    3 95 ns per loop  mean    std  dev  of 7 runs  10000000 loops each    partition         20 9   s    613 ns per loop  mean    std  dev  of 7 runs  100000 loops each    index             27 7   s    515 ns per loop  mean    std  dev  of 7 runs  10000 loops each    split  limited    27 2   s    796 ns per loop  mean    std  dev  of 7 runs  10000 loops each    split             26 5   s    377 ns per loop  mean    std  dev  of 7 runs  10000 loops each    regex             128   s    1 5   s per loop  mean    std  dev  of 7 runs  10000 loops each   String length  4294967296   regex  compiled   165 ns    1 2 ns per loop  mean    std  dev  of 7 runs  10000000 loops each    partition         19 9   s    144 ns per loop  mean    std  dev  of 7 runs  100000 loops each    index             27 7   s    571 ns per loop  mean    std  dev  of 7 runs  10000 loops each    split  limited    26 1   s    472 ns per loop  mean    std  dev  of 7 runs  10000 loops each    split             28 1   s    1 69   s per loop  mean    std  dev  of 7 runs  10000 loops each    regex             137   s    6 53   s per loop  mean    std  dev  of 7 runs  10000 loops each

User · Answer

Just use the split function  It returns a list  so you can keep the first element    gt  gt  gt  s1 split        Username     How are you today     gt  gt  gt  s1 split      0   Username

User · Answer

Using index   gt  gt  gt  string    quot Username  How are you today  quot   gt  gt  gt  string  string index  quot   quot     Username   The index will give you the position of   in string  then you can slice it  If you want to use regex   gt  gt  gt  import re  gt  gt  gt  re match  quot        quot  string  group    Username                          match matches from the start of the string  you can also use itertools takewhile  gt  gt  gt  import itertools  gt  gt  gt   quot  quot  join itertools takewhile lambda x  x   quot   quot   string    Username

[python] How would I get everything before a : in a string Python

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