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Reputation: 5347

read a number at the end of a file

I have a series of textfiles. They all end with a float, without a preceding whitespace ...foo123.456. The float has an unbounded number of digits.

the files are large so I would like to avoid reading them completely in memory. They have also different sizes.

How to avoid readgin the entire file?

Upvotes: 0

Views: 56

Answers (1)

Paulo Scardine
Paulo Scardine

Reputation: 77349

Just read the last few bytes and use a regular expression in order to extract the float number.

Untested:

import re

with open('/path/to/file.txt') as input_file:
    input_file.seek(-100, 2)
    last_100_bytes = input_file.read()
    match = re.search(r'\D(\d+\.\d+)$', last_100_bytes)
    if match:
        print('The float is {}'.format(match.group(0)))
    else:
        print('no float found at the end of the file')

Upvotes: 2

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