How Can I Efficiently Count Item Occurrences in a Python List Using Dictionaries?

Counting Items in a List with Dictionaries

Suppose you have a list of items such as:

['apple', 'red', 'apple', 'red', 'red', 'pear']

You want to create a dictionary that counts how many times each item appears in the list. For the given example, the result should be:

{'apple': 2, 'red': 3, 'pear': 1}

To achieve this task efficiently in Python, consider leveraging a dictionary. Here's how you can do it:

from collections import defaultdict

# Create a defaultdict to initialize all values to 0
item_counts = defaultdict(int)

# Iterate over the list and update counts for each item
for item in ['apple', 'red', 'apple', 'red', 'red', 'pear']:
    item_counts[item] += 1

# Print the resulting dictionary
print(item_counts)

This approach utilizes a defaultdict from the collections module, which initializes all values to 0. As you iterate over the list, you increment the count for each encountered item in the defaultdict. Finally, you'll have a detailed count of individual items in the dictionary.

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