Python function - test if given file is considered binary.

README.md

Python function - is file binary?

Function which determines if a given file is binary.

Test is based on the following algorithm (similar to that implemented within Perl):

• Empty files are considered text.
• If not empty, read up to 512 bytes as a buffer. File will be binary if:
  • Null byte is encountered.
  • More than 30% of the buffer consists of "non text" characters.
• Otherwise, file is text.

Reference

• https://eli.thegreenplace.net/2011/10/19/perls-guess-if-file-is-text-or-binary-implemented-in-python
• https://stackoverflow.com/questions/1446549/how-to-identify-binary-and-text-files-using-python/1446870#1446870

isbinary.py

#!/usr/bin/env python

class IsFileBinary:
    READ_BYTES = 512
    CHAR_THRESHOLD = 0.3
    TEXT_CHARACTERS = "".join(
        [chr(code) for code in range(32, 127)] + list("\b\f\n\r\t")
    )

    def test(self, file_path):
        # read chunk of file
        fh = open(file_path, "r")
        file_data = fh.read(IsFileBinary.READ_BYTES)
        fh.close()

        # store chunk length read
        data_length = len(file_data)
        if not data_length:
            # empty files considered text
            return False

        if "\x00" in file_data:
            # file containing null bytes is binary
            return True

        # remove all text characters from file chunk, get remaining length
        binary_length = len(file_data.translate(None, IsFileBinary.TEXT_CHARACTERS))

        # if percentage of binary characters above threshold, binary file
        return (float(binary_length) / data_length) >= IsFileBinary.CHAR_THRESHOLD


def main():
    is_file_binary = IsFileBinary()

    print("Is binary file: {0}".format(is_file_binary.test("./first")))
    print("Is binary file: {0}".format(is_file_binary.test("./second")))
    print("Is binary file: {0}".format(is_file_binary.test("./third")))


if __name__ == "__main__":
    main()

Python 3.12.3 raises a UnicodeDecodeError exception when reading a binary file opened with 'r'. Here's my no OOP approach:

def is_file_binary(file_path: str) -> bool:
    try:
        with open(file_path, 'r') as fp:
            fp.read(16)
            return False
    except UnicodeDecodeError:
            return True

Empty files reported as non-binary.

On a side note, please consider the humungous difference in simplicity, code transparency, ease of use, etc, etc, between obsessing in doing classes for every single thing or just coding it directly. If all you know is OOP, what you do every day is adjusting your problem to a predetermined solution.

If all you know is OOP, what you do every day is adjusting your problem to a predetermined solution.

one of the strangest comments I've read for a while. 😄