Python - Convert tuple list to dictionary with key from a given start value
Last Updated : 28 Apr, 2023
Given a tuple list, the following article focuses on how to convert it to a dictionary, with keys starting from a specified start value. This start value is only to give a head start, next keys will increment the value of their previous keys.
Input : test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)], start = 4 Output : {4: (4, 5), 5: (1, 3), 6: (9, 4), 7: (8, 2), 8: (10, 1)} Explanation : Tuples indexed starting key count from 4.Input : test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)], start = 6 Output : {6: (4, 5), 7: (1, 3), 8: (9, 4), 9: (8, 2), 10: (10, 1)} Explanation : Tuples indexed starting key count from 6. Method 1 : Using loop
In this, we construct the dictionary by iterating through each tuple and adding its position index, starting from start, as key-value pair in the dictionary.
Python3 # initializing list test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] # printing original list print("The original list is : " + str(test_list)) # initializing start start = 4 res = dict() for sub in test_list: # assigning positional index res[start] = sub start += 1 # printing result print("Constructed dictionary : " + str(res)) OutputThe original list is : [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] Constructed dictionary : {4: (4, 5), 5: (1, 3), 6: (9, 4), 7: (8, 2), 8: (10, 1)} Time Complexity: O(n)
Auxiliary Space: O(n)
Method 2 : Using dict() and enumerate()
In this, we convert tuple list to dictionary using dict(), and indexing is provided using enumerate().
Python3 # initializing list test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] # printing original list print("The original list is : " + str(test_list)) # initializing start start = 4 res = dict(enumerate(test_list, start=start)) # printing result print("Constructed dictionary : " + str(res)) OutputThe original list is : [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] Constructed dictionary : {4: (4, 5), 5: (1, 3), 6: (9, 4), 7: (8, 2), 8: (10, 1)} Time Complexity: O(n)
Auxiliary Space: O(n)
Using itertools.count to create an iterator for the keys:
test_list: a list of tuples
start: the starting index to use for the keys in the resulting dictionary
The function uses the zip function and the itertools.count function to create a dictionary where the keys start at start and increase by 1 for each tuple in test_list, and the values are the tuples themselves.
Python3 import itertools def tuple_list_to_dict(test_list, start): res_dict = dict(zip(itertools.count(start), test_list)) return res_dict # Example usage 1 test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] start = 4 result = tuple_list_to_dict(test_list, start) print(result) # Output : {4: (4, 5), 5: (1, 3), 6: (9, 4), 7: (8, 2), 8: (10, 1)} # Example usage 2 test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] start = 6 result = tuple_list_to_dict(test_list, start) print(result) # Output : {6: (4, 5), 7: (1, 3), 8: (9, 4), 9: (8, 2), 10: (10, 1)} Output{4: (4, 5), 5: (1, 3), 6: (9, 4), 7: (8, 2), 8: (10, 1)} {6: (4, 5), 7: (1, 3), 8: (9, 4), 9: (8, 2), 10: (10, 1)} Time complexity: O(n)
Auxiliary Space: O(n)
Method 4: Using a list comprehension with zip()
Python3 # initializing list test_list = [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] # printing original list print("The original list is: " + str(test_list)) # initializing start start = 4 # using list comprehension with zip to create dictionary res = {start+i: pair for i, pair in enumerate(test_list)} # printing result print("Constructed dictionary: " + str(res)) OutputThe original list is: [(4, 5), (1, 3), (9, 4), (8, 2), (10, 1)] Constructed dictionary: {4: (4, 5), 5: (1, 3), 6: (9, 4), 7: (8, 2), 8: (10, 1)} Time Complexity: O(n)
Auxiliary Space: O(n)
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