Given a list of lists, write a Python program to extract the last element of each sublist in the given list of lists.
Examples:
Input : [[1, 2, 3], [4, 5], [6, 7, 8, 9]] Output : [3, 5, 9] Input : [['x', 'y', 'z'], ['m'], ['a', 'b'], ['u', 'v']] Output : ['z', 'm', 'b', 'v']
Approach #1 : List comprehension
# Python3 program to extract first and last # element of each sublist in a list of lists def Extract(lst): return [item[-1] for item in lst] # Driver code lst = [[1, 2, 3], [4, 5], [6, 7, 8, 9]] print(Extract(lst)) |
[3, 5, 9]
Approach #2 : Using zip and unpacking(*) operator
This method uses zip with * or unpacking operator which passes all the items inside the ‘lst’ as arguments to zip function. There is a little trick with extracting last item of list, Instead of using direct zip, use the reversed list iterators.
# Python3 program to extract first and last # element of each sublist in a list of lists def Extract(lst): return list(zip(*[reversed(el) for el in lst]))[0] # Driver code lst = [[1, 2, 3], [4, 5], [6, 7, 8, 9]] print(Extract(lst)) |
(3, 5, 9)
Another way of using zip is to use it with Python map, passing reversed as function.
def Extract(lst): return list(list(zip(*map(reversed, lst)))[0]) |
Approach #3 : Using itemgetter()
# Python3 program to extract first and last # element of each sublist in a list of lists from operator import itemgetter def Extract(lst): return list( map(itemgetter(-1), lst )) # Driver code lst = [[1, 2, 3], [4, 5], [6, 7, 8, 9]] print(Extract(lst)) |
[3, 5, 9]
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