How Can I Efficiently Count Lines in Large Files Using Python?

Getting Line Count for Large Files in Python

Calculating the line count of large files can be a resource-intensive task. By optimizing for both efficiency and memory consumption, we can tackle this challenge effectively.

One widely adopted approach is to utilize enumeration in a for loop, as demonstrated in the provided example. However, this method can be performance-intensive.

A More Efficient Solution

For a quicker and more concise solution, we can employ the following:

num_lines = sum(1 for _ in open('myfile.txt'))

This one-line code leverages the flexibility of generator expressions to count the lines without iterating over the entire file contents and storing them in memory.

Further Performance Enhancements

To enhance speed and robustness, we can incorporate binary mode (rb) and include the code within a with block to handle file closure:

with open("myfile.txt", "rb") as f:
    num_lines = sum(1 for _ in f)

Deprecated Usage

In Python versions earlier than 3.3, the "U" in rbU mode was employed to enable universal newline support. However, this usage is obsolete, and rb mode should be used instead. Python 3.11 has removed "U" from rbU, making rb the standard option.

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