Python | Pair iteration in list
List iteration is common in programming, but sometimes one requires to print the elements in consecutive pairs. This particular problem is quite common and having a solution to it always turns out to be handy. Let’s discuss certain ways in which this problem can be solved.
Method #1 : Using list comprehension
List comprehension can be used to print the pairs by accessing current and next element in the list and then printing the same. Care has to be taken while pairing the last element with the first one to form a cyclic pair.
# Python3 code to demonstrate # pair iteration in list # using list comprehension from itertools import compress # initializing list test_list = [ 0 , 1 , 2 , 3 , 4 , 5 ] # printing original list print ( "The original list is : " + str (test_list)) # using list comprehension # to perform pair iteration in list res = [((i), (i + 1 ) % len (test_list)) for i in range ( len (test_list))] # printing result print ( "The pair list is : " + str (res)) |
Output:
The original list is : [0, 1, 2, 3, 4, 5] The pair list is : [(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 0)]
Method #2 : Using zip()
+ list slicing
zip
function can be used to extract pairs over the list and slicing can be used to successively pair the current element with the next one for the efficient pairing.
# Python3 code to demonstrate # pair iteration in list # using zip() + list slicing from itertools import compress # initializing list test_list = [ 0 , 1 , 2 , 3 , 4 , 5 ] # printing original list print ( "The original list is : " + str (test_list)) # using zip() + list slicing # to perform pair iteration in list res = list ( zip (test_list, test_list[ 1 :] + test_list[: 1 ])) # printing result print ( "The pair list is : " + str (res)) |
Output:
The original list is : [0, 1, 2, 3, 4, 5] The pair list is : [(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5,
Last Updated on March 17, 2022 by admin