Given a list, construct dictionary using key as first half values and values starting from last.
Input : test_list = [4, 10, 5, 3]
Output : {4: 3, 10: 5}
Explanation : First (4) is paired with rear (3) and so on.Input : test_list = [5, 3]
Output : {5: 3}
Explanation : First (5) is paired with rear (3).
Input : test_dict = {“Apple” : 2, “Mango” : 2, “Grapes” : 2}, {“Apple” : 2, “Mango” : 2, “Grapes” : 2}
Output : 12
Explanation : (2*2) + (2*2) + (2*2) = 12.Input : test_dict = {“Apple” : 3, “Mango” : 2, “Grapes” : 3}, {“Apple” : 2, “Mango” : 2, “Grapes” : 2}
Output : 16
Explanation : The summation of product leads to 16 as above.
Method #1 : Using loop
This is brute way in which this task can be performed. In this, we run a loop from beginning and extract values from beg-end, and construct key value mapping accordingly.
Python3
# Python3 code to demonstrate working of # Dictionary construction from front-rear key values# Using loop # initializing listtest_list = [4, 6, 3, 10, 5, 3] # printing original listprint("The original list : " + str(test_list)) # initializing size and empty Dictionaryn = len(test_list)res = dict() # running loop till midfor idx in range(n // 2): # mapping as required res.__setitem__(test_list[idx], test_list[n - idx - 1]) # printing result print("The mapped dictionary : " + str(res)) |
The original list : [4, 6, 3, 10, 5, 3]
The mapped dictionary : {4: 3, 6: 5, 3: 10}
Method #2 : Using zip() + dict()
This is yet another way in which this task can be performed. In this, we perform the task of zipping key and value elements using zip() and dict() is used to convert result to dictionary.
Python3
# Python3 code to demonstrate working of # Dictionary construction from front-rear key values# Using zip() + dict() # initializing listtest_list = [4, 6, 3, 10, 5, 3] # printing original listprint("The original list : " + str(test_list)) # using zip to cut first and second half n = len(test_list)res = dict(zip(test_list[:n // 2], test_list[n // 2:][::-1])) # printing result print("The mapped dictionary : " + str(res)) |
The original list : [4, 6, 3, 10, 5, 3]
The mapped dictionary : {4: 3, 6: 5, 3: 10}
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