How to Use Python Counters

09/09/2021

Contents

In this article, you will learn how to use Python counters.

How to Use Python Counters

The collections module in Python provides a Counter class which is used to count the number of occurrences of elements in a list, tuple, or any other iterable object.

Here’s how you can use it:

Import the collections module
import collections
Create a Counter object
# Create a Counter object from a list
my_list = [1, 1, 2, 3, 4, 5, 3, 2, 3, 4, 2, 1, 2, 3]
counter = collections.Counter(my_list)

# Create a Counter object from a string
my_string = "this is a simple sentence"
counter = collections.Counter(my_string)
Access the count of elements
# Access the count of a specific element
print(counter[2])

# Access the count of all elements
print(counter)
Perform operations with counters
# Add two counters
counter1 = collections.Counter(a=3, b=1)
counter2 = collections.Counter(a=1, b=2)
result = counter1 + counter2
print(result)

# Subtract two counters
counter1 = collections.Counter(a=3, b=1)
counter2 = collections.Counter(a=1, b=2)
result = counter1 - counter2
print(result)

Note that the counters are unordered, so the order of elements may not be the same as the order in the original list or string.

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