Sorting Python list based on the length of the string

Question

I want to sort a list of strings based on the string length  I tried to use sort as follows  but it doesn t seem to give me correct result   xs     dddd   a   bb   ccc   print xs xs sort lambda x y  len x   lt  len y   print xs    dddd    a    bb    ccc     dddd    a    bb    ccc     What might be wrong

User · Answer

def lensort list 1       list 2    list 3    for i in list 1      list 2 append  i len i    list 2 sort key   lambda x   x 1   for i in list 2      list 3 append i 0   return list 3   This works for me

User · Answer

The same as in Eli s answer - just using a shorter form  because you can skip a lambda part here    Creating new list    gt  gt  gt  xs     dddd   a   bb   ccc    gt  gt  gt  sorted xs  key len    a    bb    ccc    dddd     In-place sorting    gt  gt  gt  xs sort key len   gt  gt  gt  xs   a    bb    ccc    dddd

User · Answer

The easiest way to do this is      list sort key   lambda x len x

User · Answer

I can do it using below two methods  using function  def lensort x       list1          for i in x          list1 append  len i  i       return sorted list1   lista     a    bb    ccc    dddd   a lensort lista  print  l 1  for l in a     In one Liner  using Lambda  as below  a already answered above    lista     a    bb    ccc    dddd    lista sort key   lambda x len x    print lista

User · Answer

I Would like to add how the pythonic key function works while sorting    Decorate-Sort-Undecorate Design Pattern    Python   s support for a key function when sorting is implemented using what is known as the  decorate-sort-undecorate design pattern    It proceeds in 3 steps    Each element of the list is temporarily replaced with a    decorated    version that includes the result of the key function applied to the element  The list is sorted based upon the natural order of the keys  The decorated elements are replaced by the original elements    Key parameter to specify a function to be called on each list element prior to making comparisons  docs

User · Answer

Write a function lensort to sort a list of strings based on length    def lensort a       n   len a      for i in range n           for j in range i 1 n               if len a i    gt  len a j                    temp   a i                  a i    a j                  a j    temp     return a print lensort   hello   bye   good

User · Answer

When you pass a lambda to sort  you need to return an integer  not a boolean   So your code should instead read as follows  xs sort lambda x y  cmp len x   len y     Note that cmp is a builtin function such that cmp x  y  returns -1 if x is less than y  0 if x is equal to y  and 1 if x is greater than y  Of course  you can instead use the key parameter  xs sort key lambda s  len s    This tells the sort method to order based on whatever the key function returns  EDIT  Thanks to balpha and Ruslan below for pointing out that you can just pass len directly as the key parameter to the function  thus eliminating the need for a lambda  xs sort key len   And as Ruslan points out below  you can also use the built-in sorted function rather than the list sort method  which creates a new list rather than sorting the existing one in-place  print sorted xs  key len

[python] Sorting Python list based on the length of the string

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