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I need to do some special operation for the last element in a list. Is there any better way than this?
array = [1,2,3,4,5] for i, val in enumerate(array): if (i+1) == len(array): // Process for the last element else: // Process for the other element
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We can replace values inside the list using slicing. First, we find the index of variable that we want to replace and store it in variable 'i'. Then, we replace that item with a new value using list slicing.
Any element in list can be accessed using zero based index. If index is a negative number, count of index starts from end. As we want last element in list, use -1 as index.
Method #2 : Using islice() + reversed() The inbuilt functions can also be used to perform this particular task. The islice function can be used to get the sliced list and reversed function is used to get the elements from rear end.
for item in list[:-1]: print "Not last: ", item print "Last: ", list[-1] If you don't want to make a copy of list, you can make a simple generator:
# itr is short for "iterable" and can be any sequence, iterator, or generator def notlast(itr): itr = iter(itr) # ensure we have an iterator prev = itr.next() for item in itr: yield prev prev = item # lst is short for "list" and does not shadow the built-in list() # 'L' is also commonly used for a random list name lst = range(4) for x in notlast(lst): print "Not last: ", x print "Last: ", lst[-1] Another definition for notlast:
import itertools notlast = lambda lst:itertools.islice(lst, 0, len(lst)-1) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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