Review: Invert Dictionary

Module 4: IDEs & Tools

Invert Dictionary

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

Example: - Input: d = {"fruit": ["apple", "pear"], "veggie": ["pepper"]} - Output: {"apple": "fruit", "pear": "fruit", "pepper": "veggie"}

# Try this input too
grades = {
    9: ["Amanda", "Bert"],
    8: ["Charlie", "Denise"],
    7: ["Ernesto", "Fiona", "Gonzalo"],
    6: ["Hilda", "Ignacio", "Jerry"]
}

Solution

Try the exercise on your own first, then compare with the worked solution below.

# Solution

def invert_dict(dict_in: dict) -> dict:
  dict_out = {}

  for key, ls in dict_in.items():
    for value in ls:
      dict_out[value] = key

  return dict_out

students = invert_dict(grades)

print(students)