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up vote 902 down vote favorite
106

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

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9  
You meant alist[len(alist) - 1] -- Python lists are 0-indexed. – Dave May 30 '09 at 19:30
50  
@janusz And googling for "last element of list in Python" now takes you right here, so it's a useful resource. – gcbenison Mar 22 '12 at 16:46
up vote 1476 down vote accepted

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:

>>> some_list = [1, 2, 3]
>>> some_list[-1] = 5 # Set the last element
>>> some_list[-2] = 3 # Set the second to last element
>>> some_list
[1, 3, 5]
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1  
list[0] = 'first' list[1] = 'second' list[-1] = 'last' list[-2] = 'second last' – Renyi Jan 5 '12 at 7:04
5  
Of course, to get the first element, just use list[0]. And to get the first five elements, list[:5]. And the last five, list[-5:], etc. etc. – Alexander Apr 24 '15 at 4:14
    
What is the time complexity of this [-1], O(1)? O(n)? Thanks – computereasy Oct 1 '16 at 21:38
2  
@computereasy: It should be O(1), because it's the same thing as a[a.length - 1]. – Sasha Chedygov Oct 1 '16 at 21:54
1  
This is interesting as it is hard to find this indexing subtlety in the official Python docs! – crowie Nov 26 '16 at 12:03
up vote 124 down vote

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.

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9  
And some more magic can be done with alist[:-1]. So if you have alist = [1,2,3] then alist[:-1] = [1,2]. It's a way to get all but the last item. Great read on it here effbot.org/zone/python-list.htm – Christoffer May 27 '13 at 19:10
1  
@DevPlayer What you do with the supposed "last element" determines if you want an Exception or an empty str/list object. if your list is a list of lists then you want to use alist[-1] instead of alist[-1:]. You don't want a false list object -> [] <- returned but an exception if the parent list is empty. If on the other hand you are testing the last element as an object like so `if alist[-1:]: dostuff() then if you get an empty str/list then using alist[-1:] is prefered. – DevPlayer Apr 28 '15 at 2:41
2  
Downvoted because I feel the core of this answer is incorrect. Getting a list when you want an element only postpones the inevitable "list index out of range" - and that's what should happen when attempting to get an element from an empty list. For Strings astr[-1:] could be a valid approach since it returns the same type as astr[-1], but I don't think the ':' helps to deal with empty lists (and the question is about lists). If the idea is to use "alist[-1:]" as a conditional instead of "len(alist) > 0", I think it's much more readable to use the later. (happy to upvote if I missed something) – Stan Kurdziel Jun 7 '15 at 6:27
1  
You're down vote is understandable and valid. However I find there are two basic camps on what exception objects are intended for. One certainty is that exceptions halt your app. One camp uses exceptions in try clauses as the other camp would use the if len(alist)>0: structure instead. In any event, exceptions are objects that halt your code. And as such to me are less sequence object like then returned "null"-sequences which do not halt your code. My preference is to use IF clauses to test for "null" objects instead of objects that halt my code that I preempt with a try clause. – DevPlayer Jun 8 '15 at 20:58
    
My answer was offered to address a fringe case to the OP's question, "How do get the last element of a list". Problem with that question is that it presumes there is a last element. When there isn't, there are ways to handle that "exception". But one shouldn't presume that the application actually needs the last element, perhaps it is just asking if there is a last element. I can think of many use-cases where jumping through hoops to handle the exception isn't necessary or important. So using the exception handling approach may not be the best structure. – DevPlayer Jun 8 '15 at 21:05
up vote 50 down vote

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.

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up vote 35 down vote

The simplest way to display last element in python is

>>> list[-1:] # returns indexed value
    [3]
>>> list[-1]  # returns value
    3

there are many other method to achieve such a goal but these are short and sweet to use.

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up vote 5 down vote

some_list = [1, 2, 3]

Method 1:

some_list[-1]

Method 2:

**some_list.reverse()** 

**some_list[0]**

Method 3:

some_list.pop()
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Methods 1 and 3 have been mentioned years ago and Method 2 is so inefficient it is not worth mentioning – Chris_Rands Jan 25 at 16:21
up vote 1 down vote

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.

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It's probably bad to assume that mutating the original list is usually not recommended, because, after all, it is very commonly carried out – Aaron Dec 1 '16 at 11:34
up vote 0 down vote

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.

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1  
items[len(items) - 1] is essentially what Python is doing under the hood, but since the len of a sequence is already stored in the sequence there is no need to count it, you're creating more work than is necessary. – Dan Gayle Oct 10 '15 at 0:25
10  
since you're writing Python, you really should try to be more Pythonic – Michael Wu Oct 27 '15 at 3:35
4  
@MichaelWu There is no sense to do that. Pythonic way often is not self-explanatory, need more attention where you have to introduce new persons to project and, of course, wouldn't work when you have to switch to other languages like Java - you can't use Python specific knowledge. When you omit pythonic way as is possible, then also returning to project after months/years is much easier. – Pneumokok Oct 31 '15 at 14:13
6  
@Pneumokok You make point, but I would argue that list indexing is a very basic Python technique compared to say generators. Also, why bother to use anything other than C or maybe javascript if you aren't going to take advantage of individual language tools and syntax? Then you can be consistently doing everything the hard way in all of your projects. – Matthew Purdon Dec 3 '15 at 15:30
    
Although it's not very pythonic I think this is in some respects better than the some_list[-1] approach because it's more logical, and shows what it is actually doing better than some_list[-1] in my opinion. – Byron Filer Nov 4 '16 at 21:08
up vote -9 down vote 
popes = ['john paul II', 'benedict XIV', 'francis I']
current_pope = []
for pope in popes:
     current_pope = pope

after the for loop you'll get last item in current_pope variable.

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6  
That's just unnecessary looping. Why would you not index it directly? – steinar Aug 9 '15 at 11:04
    
Why are you defining current_pope as a list, when it becomes a string in the loop? Furthermore, why are you even defining that variable before the loop? – imolit Dec 15 '16 at 9:50

protected by Jim Fasarakis-Hilliard Dec 14 '16 at 17:06

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