How to sort with lambda in Python

Question

In Python  I am trying to sort by date with lambda   I can t understand my error message  The message is    lt lambda gt    takes exactly 1 argument  2 given    The line I have is  a   sorted a  lambda x  x modified  reverse True

User · Answer

lst      candy   30   100      apple   10   200      baby   20   300    lst sort key lambda x x 1   print lst    It will print as following      apple    10    200      baby    20    300      candy    30    100

User · Answer

Use  a   sorted a  key lambda x  x modified  reverse True                       On Python 2 x  the sorted function takes its arguments in this order   sorted iterable  cmp None  key None  reverse False    so without the key   the function you pass in will be considered a cmp function which takes 2 arguments

User · Answer

You re trying to use key functions with lambda functions  Python and other languages like C  or F  use lambda functions  Also  when it comes to key functions and according to the documentation  Both list sort   and sorted   have a key parameter to specify a function to be called on each list element prior to making comparisons      The value of the key parameter should be a function that takes a single argument and returns a key to use for sorting purposes  This technique is fast because the key function is called exactly once for each input record   So  key functions have a parameter key and it can indeed receive a lambda function  In Real Python there s a nice example of its usage  Let s say you have the following list ids     id1    id100    id2    id22    id3    id30    and want to sort through its  quot integers quot   Then  you d do something like sorted ids   sorted ids  key lambda x  int x 2       Integer sort  and printing it would give   id1    id2    id3    id22    id30    id100    In your particular case  you re only missing to write key  before lambda  So  you d want to use the following a   sorted a  key lambda x  x modified  reverse True

[python] How to sort with lambda in Python

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