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Python: Grouping a sequence of key-value pairs into a dictionary of lists using collections module

Python Collections: Exercise-28 with Solution

Write a Python program to create a dictionary grouping a sequence of key-value pairs into a dictionary of lists. Use collections module.

Sample Solution:

Python Code:

from collections import defaultdict
def grouping_dictionary(l):
    d = defaultdict(list)
    for k, v in l:
        d[k].append(v)
    return d
colors = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
print("Original list:")
print(colors)
print("\nGrouping a sequence of key-value pairs into a dictionary of lists:")
print(grouping_dictionary(colors))

Sample Output:

Original list:
[('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]

Grouping a sequence of key-value pairs into a dictionary of lists:
defaultdict(<class 'list'>, {'yellow': [1, 3], 'blue': [2, 4], 'red': [1]})

Flowchart:

Python Collections: Grouping a sequence of key-value pairs into a dictionary of lists using collections module.

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Python: Tips of the Day

Inverts a dictionary with unique hashable values:

Example:

def tips_invert_dictionary(obj):
  return { value: key for key, value in obj.items() }
ages = {
  "Owen": 29,
  "Eddie": 15,
  "Jhon": 22,
}
print(tips_invert_dictionary(ages))

Output:

{29: 'Owen', 15: 'Eddie', 22: 'Jhon'}