Python: Group a sequence of key-value pairs into a dictionary of lists

Python Collections: Exercise-35 with Solution

Write a Python program to group a sequence of key-value pairs into a dictionary of lists.

Sample Solution:

Python Code:

from collections import defaultdict
class_roll = [('v', 1), ('vi', 2), ('v', 3), ('vi', 4), ('vii', 1)]
d = defaultdict(list)
for k, v in class_roll:
    d[k].append(v)
print(sorted(d.items()))

Sample Output:

[('v', [1, 3]), ('vi', [2, 4]), ('vii', [1])]

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