How can I detect if a file is binary (non-text) in Python?

python file binary
grieve picture grieve · May 22, 2009 · Viewed 69.3k times · Source

How can I tell if a file is binary (non-text) in Python?

I am searching through a large set of files in Python, and keep getting matches in binary files. This makes the output look incredibly messy.

I know I could use grep -I, but I am doing more with the data than what grep allows for.

In the past, I would have just searched for characters greater than 0x7f, but utf8 and the like, make that impossible on modern systems. Ideally, the solution would be fast.

Answer

jfs picture jfs · Sep 12, 2011

Yet another method based on file(1) behavior:

>>> textchars = bytearray({7,8,9,10,12,13,27} | set(range(0x20, 0x100)) - {0x7f})
>>> is_binary_string = lambda bytes: bool(bytes.translate(None, textchars))

Example:

>>> is_binary_string(open('/usr/bin/python', 'rb').read(1024))
True
>>> is_binary_string(open('/usr/bin/dh_python3', 'rb').read(1024))
False

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