How to make a regexp matching for a row of bytes?
For example how to check with regexp that binary data consists of (0-10 byte) characters?
data = 0x00 0x05 0x02 0x00 0x03 ... (not a string, binary data)
3 Answers
If you want to check that the string contains only characters between chr(0) and chr(10), simply use
re.match('^[\0-\x0A]*$',data)
For Python3, you can do the same with byte strings:
re.match(b'^[\0-\x0A]*$',b'\x01\x02\x03\x04')
Comments
This will match any code before space:
if re.search('[\0-\037]', line):
# Contains binary data...
I'm not sure what you mean by "0-10 byte", but if you mean that you want to match only the byte values 0 to 10, then replace \037 with \012 in the above code.
Note that 0-10 aren't really the only codes that would suggest binary data; anything below \040 or above \0177 usually suggests binary data.
Comments
If you want check if all characters in the given string are in the range 0x00 to 0x0B (not inclusive), regex is way overkill. Try something like this:
>>> check_range = lambda x: ord(x) in set(range(0x00, 0x0B))
>>> s = '\x1\x2\x3\xA'
>>> s2 = 'abcde'
>>> print all(check_range(c) for c in s)
True
>>> print all(check_range(c) for c in s2)
False
>>>
2 Comments
Sergey
I tested it with timeit module, short string s (5 symbols), million executions. Regexp wins (3.5x faster)
Chinmay Kanchi
My own tests bear this out. I would delete this answer, but your comment is useful. With some optimization, I managed to bring it down to about 1.3x the speed of the regex version, but not below it.
reprof some data (e.g.print repr(data[:50])) that you have? It's not clear if you have binary data or a hex representation of such in a string.