Python: Invert a given dictionary with non-unique hashable values

Last update on December 21 2024 07:28:38 (UTC/GMT +8 hours)

Write a Python program to invert a given dictionary with non-unique hashable values.

• Create a collections.defaultdict with list as the default value for each key.
• Use dictionary.items() in combination with a loop to map the values of the dictionary to keys using dict.append().
• Use dict() to convert the collections.defaultdict to a regular dictionary.

Sample Solution:

Python Code:

# Import the 'defaultdict' class from the 'collections' module.
from collections import defaultdict

# Define a function 'test' that takes a dictionary 'students' as an argument.
def test(students):
  # Create a 'defaultdict' object 'obj' with a default value of an empty list.
  obj = defaultdict(list)

  # Iterate through the items (key-value pairs) in the 'students' dictionary.
  for key, value in students.items():
    # Append the 'key' to the list associated with the 'value' in the 'obj' dictionary.
    obj[value].append(key)

  # Convert the 'defaultdict' 'obj' back to a regular dictionary and return it.
  return dict(obj)

# Define a dictionary 'students' with student names as keys and grades as values.
students = {
  'Ora Mckinney': 8,
  'Theodore Hollandl': 7,
  'Mae Fleming': 7,
  'Mathew Gilbert': 8,
  'Ivan Little': 7,
}

# Call the 'test' function with the 'students' dictionary and print the result.
print(test(students))

Sample Output:

{8: ['Ora Mckinney', 'Mathew Gilbert'], 7: ['Theodore Hollandl', 'Mae Fleming', 'Ivan Little']}

Flowchart:

Python Code Editor:

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