How Can I Efficiently and Accurately Count Lines in a Large File Using Python?

Line Counting Optimization in Python: Achieving Accuracy and Efficiency

Counting line counts in large files efficiently requires both memory optimization and time efficiency. One common technique is using a for loop, but this can impact memory consumption.

A more efficient approach is the single-liner:

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

This comprehension counts the lines in the file by iterating over it and using the 1 value as a counter. However, for even greater speed and robustness, a modification can be made:

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

Using rbU mode improves speed, but it's deprecated in Python 3.3 and above. Thus, using rb instead is recommended. In Python 3.11, the U flag has been removed.

Remember that these solutions are designed to be memory-efficient while maintaining accurate line counts. The choice of technique depends on specific requirements and performance considerations.

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