Getting the last element of a list

Question

In Python  how do you get the last element of a list

User · Answer

If you do my list -1  this returns the last element of the list  Negative sequence indexes represent positions from the end of the array  Negative indexing means beginning from the end  -1 refers to the last item  -2 refers to the second-last item  etc

User · Answer

some list -1  is the shortest and most Pythonic  In fact  you can do much more with this syntax  The some list -n  syntax gets the nth-to-last element  So some list -1  gets the last element  some list -2  gets the second to last  etc  all the way down to some list -len some list    which gives you the first element  You can also set list elements in this way  For instance   gt  gt  gt  some list    1  2  3   gt  gt  gt  some list -1    5   Set the last element  gt  gt  gt  some list -2    3   Set the second to last element  gt  gt  gt  some list  1  3  5   Note that getting a list item by index will raise an IndexError if the expected item doesn t exist  This means that some list -1  will raise an exception if some list is empty  because an empty list can t have a last element

User · Answer

You can also use the code below  if you do not want to get IndexError when the list is empty   next reversed some list   None

User · Answer

Another method   some list reverse    some list 0

User · Answer

lst -1  is the best approach  but with general iterables  consider more itertools last   Code  import more itertools as mit   mit last  0  1  2  3     3  mit last iter  1  2  3      3  mit last      some default      some default

User · Answer

You can also do   alist pop     It depends on what you want to do with your list because the pop   method will delete the last element

User · Answer

In Python  how do you get the last element of a list    To just get the last element     without modifying the list  and  assuming you know the list has a last element  i e  it is nonempty     pass -1 to the subscript notation    gt  gt  gt  a list     zero    one    two    three    gt  gt  gt  a list -1   three    Explanation  Indexes and slices can take negative integers as arguments   I have modified an example from the documentation to indicate which item in a sequence each index references  in this case  in the string  Python   -1 references the last element  the character   n      --- --- --- --- --- ---     P   y   t   h   o   n     --- --- --- --- --- ---     0   1   2   3   4   5    -6  -5  -4  -3  -2  -1   gt  gt  gt  p    Python   gt  gt  gt  p -1   n    Assignment via iterable unpacking  This method may unnecessarily materialize a second list for the purposes of just getting the last element  but for the sake of completeness  and since it supports any iterable - not just lists     gt  gt  gt   head  last   a list  gt  gt  gt  last  three    The variable name  head is bound to the unnecessary newly created list    gt  gt  gt  head   zero    one    two     If you intend to do nothing with that list  this would be more apropos       last   a list   Or  really  if you know it s a list  or at least accepts subscript notation    last   a list -1    In a function  A commenter said      I wish Python had a function for first   and last   like Lisp does    it would get rid of a lot of unnecessary lambda functions    These would be quite simple to define   def last a list       return a list -1   def first a list       return a list 0    Or use operator itemgetter    gt  gt  gt  import operator  gt  gt  gt  last   operator itemgetter -1   gt  gt  gt  first   operator itemgetter 0    In either case    gt  gt  gt  last a list   three   gt  gt  gt  first a list   zero    Special cases  If you re doing something more complicated  you may find it more performant to get the last element in slightly different ways   If you re new to programming  you should avoid this section  because it couples otherwise semantically different parts of algorithms together  If you change your algorithm in one place  it may have an unintended impact on another line of code    I try to provide caveats and conditions as completely as I can  but I may have missed something  Please comment if you think I m leaving a caveat out   Slicing  A slice of a list returns a new list - so we can slice from -1 to the end if we are going to want the element in a new list    gt  gt  gt  a slice   a list -1    gt  gt  gt  a slice   three     This has the upside of not failing if the list is empty    gt  gt  gt  empty list       gt  gt  gt  tail   empty list -1    gt  gt  gt  if tail          do something tail    Whereas attempting to access by index raises an IndexError which would need to be handled    gt  gt  gt  empty list -1  Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt  IndexError  list index out of range   But again  slicing for this purpose should only be done if you need    a new list created and the new list to be empty if the prior list was empty    for loops  As a feature of Python  there is no inner scoping in a for loop   If you re performing a complete iteration over the list already  the last element will still be referenced by the variable name assigned in the loop    gt  gt  gt  def do something arg   pass  gt  gt  gt  for item in a list          do something item            gt  gt  gt  item  three    This is not semantically the last thing in the list  This is semantically the last thing that the name  item  was bound to    gt  gt  gt  def do something arg   raise Exception  gt  gt  gt  for item in a list          do something item      Traceback  most recent call last     File   lt stdin gt    line 2  in  lt module gt    File   lt stdin gt    line 1  in do something Exception  gt  gt  gt  item  zero    Thus this should only be used to get the last element if you    are already looping  and  you know the loop will finish  not break or exit due to errors   otherwise it will point to the last element referenced by the loop    Getting and removing it  We can also mutate our original list by removing and returning the last element    gt  gt  gt  a list pop -1   three   gt  gt  gt  a list   zero    one    two     But now the original list is modified     -1 is actually the default argument  so list pop can be used without an index argument     gt  gt  gt  a list pop    two    Only do this if   you know the list has elements in it  or are prepared to handle the exception if it is empty  and you do intend to remove the last element from the list  treating it like a stack     These are valid use-cases  but not very common   Saving the rest of the reverse for later   I don t know why you d do it  but for completeness  since reversed returns an iterator  which supports the iterator protocol  you can pass its result to next    gt  gt  gt  next reversed  1 2 3    3   So it s like doing the reverse of this    gt  gt  gt  next iter  1 2 3    1   But I can t think of a good reason to do this  unless you ll need the rest of the reverse iterator later  which would probably look more like this   reverse iterator   reversed  1 2 3   last element   next reverse iterator   use later   list reverse iterator    and now    gt  gt  gt  use later  2  1   gt  gt  gt  last element 3

User · Answer

Here is the solution for your query  a   quot first quot   quot middle quot   quot last quot     A sample list print a 0    prints the first item in the list because the index of the list always starts from 0  print a -1    prints the last item in the list  print a -2    prints the last second item in the list   Output   gt  gt  gt  first  gt  gt  gt  last  gt  gt  gt  middle

User · Answer

The simplest way to display last element in python is   gt  gt  gt  list -1     returns indexed value      3   gt  gt  gt  list -1     returns value     3   there are many other method to achieve such a goal but these are short and sweet to use

User · Answer

To prevent IndexError  list index out of range  use this syntax   mylist    1  2  3  4     With None as default value  value   mylist and mylist -1     With specified default value  option 1   value   mylist and mylist -1  or  default     With specified default value  option 2   value   mylist -1  if mylist else  default

User · Answer

Ok  but what about common in almost every language way items len items  - 1   This is IMO the easiest way to get last element  because it does not require anything pythonic knowledge

User · Answer

If your str   or list   objects might end up being empty as so  astr      or alist       then you might want to use alist -1   instead of alist -1  for object  sameness    The significance of this is   alist      alist -1      will generate an IndexError exception whereas  alist -1      will return an empty list astr      astr -1       will generate an IndexError exception whereas astr -1       will return an empty str   Where the distinction being made is that returning an empty list object or empty str object is more  last element -like then an exception object

User · Answer

list -1  will retrieve the last element of the list without changing the list  list pop   will retrieve the last element of the list  but it will mutate change the original list  Usually  mutating the original list is not recommended   Alternatively  if  for some reason  you re looking for something less pythonic  you could use list len list -1   assuming the list is not empty

[python] Getting the last element of a list

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