Frequency Analysis of List Elements

Introduction

In this challenge, you will create a Python function that takes a list as an argument and returns a dictionary with the unique values of the list as keys and their frequencies as the values. This is a common task in data analysis and can be useful in many different applications.

Value Frequencies

Write a Python function called value_frequencies(lst) that takes a list as an argument and returns a dictionary with the unique values of the list as keys and their frequencies as the values.

To solve this problem, you can follow these steps:

1. Create an empty dictionary to store the frequencies of each unique element.
2. Loop through the list and use collections.defaultdict to store the frequencies of each unique element.
3. Use dict() to return a dictionary with the unique elements of the list as keys and their frequencies as the values.

Your function should return the dictionary with the unique values and their frequencies.

from collections import defaultdict

def frequencies(lst):
  freq = defaultdict(int)
  for val in lst:
    freq[val] += 1
  return dict(freq)

frequencies(['a', 'b', 'a', 'c', 'a', 'a', 'b']) ## { 'a': 4, 'b': 2, 'c': 1 }

Summary

In this challenge, you learned how to create a Python function that takes a list as an argument and returns a dictionary with the unique values of the list as keys and their frequencies as the values. This is a useful technique in data analysis and can be used in many different applications.