Python - Words Frequency in String Shorthands

Given a string, the task is to find how many times each word appears in it. For example, the string "hello world hello everyone" should output each word with its frequency count.

Example:

Input: "hello world hello everyone"
Output: {'hello': 2, 'world': 1, 'everyone': 1}

Let’s explore different methods to find word frequency in Python.

Using collections.Counter

Counter() automatically counts how many times each word appears in a list when you split the string into words using .split().

Counter({'hello': 2, 'world': 1, 'everyone': 1})

Explanation:

• s.split() splits the string into a list of words.
• Counter() counts how many times each unique word appears.
• The result shows 'hello' appears twice, 'world' and 'everyone' once each.

Using dict.get() with a for loop

Using dict.get() with a for loop allows you to efficiently count occurrences of each character or word in a string. The get() method retrieves the current count and if the character or word isn't in the dictionary yet, it returns a default value (usually 0).

{'hello': 2, 'world': 1, 'everyone': 1}

Explanation:

• for word in s.split() iterates through each word.
• w_freq.get(word, 0) fetches the word’s count (or 0 if it’s new).
• The count is incremented by 1 for every occurrence.

Using defaultdict(int) from collections

This is another efficient dictionary-based approach where every missing key is automatically initialized to 0.

{'hello': 2, 'world': 1, 'everyone': 1}

Explanation:

• defaultdict(int) automatically starts each new key with 0.
• For each word, res[word] += 1 increments the count.

Using List Comprehension with collections.Counter

Using list comprehension with collections.Counter allows you to efficiently count the frequency of elements by transforming the data (such as characters or words in a string) and applying Counter to generate frequency counts.

Counter({'hello': 2, 'world': 1, 'everyone': 1})

Explanation:

• [word for word in s.split()] creates a list of all words.
• Counter() then counts each word’s occurrence.