How to Efficiently Count Item Frequencies in Python: Using the Counter Class?

Item Frequency Count in Python: A More Efficient Approach

Problem:

Finding the number of occurrences of each item in a list of words is a common task in text processing. A straightforward approach involves creating a set of unique words and then counting their instances within the list. However, this method is inefficient as it iterates twice over the list.

More Efficient and Pythonic Solution:

To improve efficiency, Python offers the collections.Counter class, specifically designed for counting items in a collection.

Code:

<code class="python">from collections import Counter
words = "apple banana apple strawberry banana lemon"
print(Counter(words.split()))</code>

Output:

Counter({'apple': 2, 'banana': 2, 'strawberry': 1, 'lemon': 1})

Advantages:

• The Counter class simplifies the counting process, requiring only one iteration over the data.
• It automatically tracks the count for each unique item, making it easy to access the frequencies.
• Unlike the previous approach, the Counter class can also handle counting items in more complex data structures, such as dictionaries.

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