Convert Tuple Value List to List of Tuples – Python
Last Updated : 21 Jan, 2025
We are given a dictionary with values as a list of tuples and our task is to convert it into a list of tuples where each tuple consists of a key and its corresponding value. Note: Each key will appear with each value from the list of tuples. For example: We have a dictionary dict = {‘Gfg’ : [(5, ), (6, )], ‘is’ : [(5, )], ‘best’ :[(7, )]} then output will be [(‘Gfg’, 5), (‘Gfg’, 6), (‘is’, 5), (‘best’, 7)]
Using * Operator ( unpacking operator)
In this method we iterate through the dictionary and use the unpacking * operator to extract values from the tuples and map them to their respective keys.
Python d = {'Gfg' : [(5, ), (6, )], 'is' : [(5, )], 'best' :[(7, )]} # using items() to extract all items and pair key with tuple values res = [] for k, v in d.items(): for ele in v: res.append((k, *ele)) print("Converted tuple list: " + str(res)) OutputConverted tuple list: [('Gfg', 5), ('Gfg', 6), ('is', 5), ('best', 7)] Let’s explore other methods to achieve the same:
Using List Comprehension + * Operator
This method is quite similar to using * Operator ( unpacking operator) method but the only difference is that we get a one-liner solution using list comprehension.
Python d = {'Gfg' : [(5, ), (6, )], 'is' : [(5, )], 'best' :[(7, )]} # list comprehension to pair key with tuple values res = [(k, *ele) for k, v in d.items() for ele in v] print("Converted tuple list: " + str(res)) OutputConverted tuple list: [('Gfg', 5), ('Gfg', 6), ('is', 5), ('best', 7)] Using map() and lambda Function
map() function with a lambda is used to transform each key-value pair from the dictionary. For each key-value pair, it creates a list of tuples where the key is prepended to the unpacked tuple values and at last the nested list is flattened using list comprehension.
Python d = {'Gfg': [(5, ), (6, )], 'is': [(5, )], 'best':[(7, )]} # map and lambda to pair key with tuple values res = list(map(lambda x: [(x[0], *y) for y in x[1]], d.items())) res = [item for sublist in res for item in sublist] print("Converted tuple list: " + str(res)) OutputConverted tuple list: [('Gfg', 5), ('Gfg', 6), ('is', 5), ('best', 7)] Explanation: lambda x: [(x[0], *y) for y in x[1]] takes the key (x[0]) and prepends it to each tuple in the value list (x[1]) and the * operator unpacks the tuple into separate elements.
Using a dictionary comprehension
This method uses dictionary comprehension to first create a new dictionary where each key is prepended to its corresponding tuples then it flattens the result into a single list using a list comprehension.
Python d = {'Gfg': [(5, 6, 7), (1, 3), (6, )], 'is': [(5, 5, 2, 2, 6)], 'best': [(7,), (9, 16)]} # using dictionary comprehension to prepend key to each tuple p_dict = {k: [(k, *t) for t in v] for k, v in d.items()} # flattening the result res = [i for sublist in p_dict.values() for i in sublist] print("The converted tuple list : " + str(res)) OutputThe converted tuple list : [('Gfg', 5, 6, 7), ('Gfg', 1, 3), ('Gfg', 6), ('is', 5, 5, 2, 2, 6), ('best', 7), ('best', 9, 16)] Explanation:
{k: [(k, *t) for t in v] for k, v in d.items()} this line creates a list of tuples where each tuple is formed by prepending the key k to each tuple t in the list v. and the * operator is used to unpack the tuples.[item for sublist in prepended_dict.values() for item in sublist] this list comprehension flattens the result by iterating over the values of the newly created dictionary (pre_dict) which are lists of tuples and adding each tuple to the final res list.
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