Given a list, convert it into dictionary by mapping alternate elements as key-value pairs.
Input : test_list = [2, 3, 5, 6, 7, 8]
Output : {3: 6, 6: 8, 2: 5, 5: 7}
Explanation : Alternate elements mapped to get key-value pairs. 3 -> 6 [ alternate]Input : test_list = [2, 3, 5, 6]
Output : {3: 6, 2: 5}
Explanation : Alternate elements mapped to get key-value pairs. 3 -> 6 [ alternate]
Method #1 : Using loop
This is one of the ways in which this task can be performed. In this, we iterate twice to get both the alternate elements to get desired all alternate key-value dictionary.
Python3
# Python3 code to demonstrate working of # Alternate Elements Dictionary # Using loop # initializing list test_list = [2, 3, 5, 6, 7, 8, 9, 10] # printing original list print("The original list is : " + str(test_list)) res = dict() # pairing first set of Alternate elements for idx in range(len(test_list) - 2): if idx % 2: res[test_list[idx]] = test_list[idx + 2] # pairing other set for idx in range(len(test_list) - 2): if not idx % 2: res[test_list[idx]] = test_list[idx + 2] # printing result print("The extracted dictionary : " + str(res)) |
The original list is : [2, 3, 5, 6, 7, 8, 9, 10]
The extracted dictionary : {3: 6, 6: 8, 8: 10, 2: 5, 5: 7, 7: 9}
Method #2 : Using dictionary comprehension + list slicing
This is yet another way in which this task can be performed. In this, we slice out both alternate elements lists and use dictionary comprehension for pairing.
Python3
# Python3 code to demonstrate working of # Alternate Elements Dictionary # Using dictionary comprehension + list slicing # initializing list test_list = [2, 3, 5, 6, 7, 8, 9, 10] # printing original list print("The original list is : " + str(test_list)) # extracting lists list1 = test_list[1::2] list2 = test_list[::2] # constructing pairs using dictionary comprehension res = {list1[idx] : list1[idx + 1] for idx in range(len(list1) - 1)} res.update({list2[idx] : list2[idx + 1] for idx in range(len(list2) - 1)}) # printing result print("The extracted dictionary : " + str(res)) |
The original list is : [2, 3, 5, 6, 7, 8, 9, 10]
The extracted dictionary : {3: 6, 6: 8, 8: 10, 2: 5, 5: 7, 7: 9}
