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Python: Create a dictionary with the unique values of a list as keys and their frequencies as the values

Python List: Exercise - 241 with Solution

Write a Python program to create a dictionary with the unique values of a given list as keys and their frequencies as the values.

  • Use collections.defaultdict() to store the frequencies of each unique element.
  • Use dict() to return a dictionary with the unique elements of the list as keys and their frequencies as the values.

Sample Solution:

Python Code:

from collections import defaultdict
def frequencies(lst):
  freq = defaultdict(int)
  for val in lst:
    freq[val] += 1
  return dict(freq) 
print(frequencies(['a', 'b', 'f', 'a', 'c', 'e', 'a', 'a', 'b', 'e', 'f'])) 
print(frequencies([3,4,7,5,9,3,4,5,0,3,2,3]))

Sample Output:

{'a': 4, 'b': 2, 'f': 2, 'c': 1, 'e': 2}
{3: 4, 4: 2, 7: 1, 5: 2, 9: 1, 0: 1, 2: 1}

Flowchart:

Flowchart: Create a dictionary with the unique values of a list as keys and their frequencies as the values.

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Python: Tips of the Day

Big Number Readability:

you can separate zeros with underscore (_)

print(2_000_000)
print(2_000_000 +1)

Output:

2000000
2000001