Appending the same string to a list of strings in Python

Question

I am trying to take one string  and append it to every string contained in a list  and then have a new list with the completed strings  Example  list1     foo    fob    faz    funk   string    bar    magic   list2     foobar    fobbar    fazbar    funkbar    I tried for loops  and an attempt at list comprehension  but it was garbage  As always  any help  much appreciated

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list2      sbar     x   for x in list    And don t use list as a name  it shadows the built-in type

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Just in case  list     foo    fob    faz    funk   string    bar  for i in range len list        list i     string print list

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my list     foo    fob    faz    funk   string    bar  my new list    x   string for x in my list  print my new list   This will print     foobar    fobbar    fazbar    funkbar

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map seems like the right tool for the job to me   my list     foo    fob    faz    funk   string    bar  list2   list map lambda orig string  orig string   string  my list     See this section on functional programming tools for more examples of map

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Running the following experiment the pythonic way    s   mystring for s in mylist    seems to be  35  faster than the obvious use of a for loop like this   i   0 for s in mylist      mylist i    s mystring     i   i   1   Experiment  import random import string import time  mystring     test    l      ref list       for i in xrange  10  6        ref list append     join random choice string ascii lowercase  for i in range 10      for numOfElements in  5  10  15         l   ref list numOfElements     print  Number of elements    len l       l1   list  l       l2   list  l          Method A     start time   time time       l2    s   mystring for s in l2      stop time   time time       dt1   stop time - start time     del l2        print  Method A   s seconds     dt1         Method B     start time   time time       i   0     for s in l1          l1 i    s mystring         i   i   1     stop time   time time       dt0   stop time - start time     del l1     del l        print  Method B   s seconds     dt0       print  Method A is   1f   faster than Method B      1 - dt1 dt0  100    Results  Number of elements  5000000 Method A is 38 4  faster than Method B Number of elements  10000000 Method A is 33 8  faster than Method B Number of elements  15000000 Method A is 35 5  faster than Method B

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Extending a bit to  Appending a list of strings to a list of strings        import numpy as np     lst1     a   b   c   d   e       lst2     1   2   3   4   5        at   np full fill value     shape len lst1  dtype object   optional third list     result   np array lst1 dtype object  at np array lst2 dtype object    Result   array   a 1    b 2    c 3    d 4    e 5    dtype object    dtype odject may be further converted str

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new list    word in list   end string for word in list in old list    Using names such as  list  for your variable names is bad since it will overwrite override the builtins

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you can use lambda inside map in python  wrote a gray codes generator  https   github com rdm750 rdm750 github io blob master python gray code generator py           your code goes here                     the n-1 bit code  with 0 prepended to each word  followed by         the n-1 bit code in reverse order  with 1 prepended to each word                   def graycode n           if n  1              return   0   1           else              nbit map lambda x  0  x graycode n-1   map lambda x  1  x graycode n-1    -1               return nbit      for i in xrange 1 7           print map int graycode i

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Updating with more options  list1     foo    fob    faz    funk   addstring    bar  for index  value in enumerate list1       list1 index    addstring   value  this will prepend the string      list1 index    value   addstring this will append the string    Avoid using keywords as variables like  list   renamed  list  as  list1  instead

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Here is a simple answer using pandas   import pandas as pd list1     foo    fob    faz    funk   string    bar   list2    pd Series list1    string  tolist   list2     foobar    fobbar    fazbar    funkbar

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The simplest way to do this is with a list comprehension    s   mystring for s in mylist    Notice that I avoided using builtin names like list because that shadows or hides the builtin names  which is very much not good   Also  if you do not actually need a list  but just need an iterator  a generator expression can be more efficient  although it does not likely matter on short lists     s   mystring for s in mylist    These are very powerful  flexible  and concise   Every good python programmer should learn to wield them

[python] Appending the same string to a list of strings in Python

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