Convert list of byte strings to bytearray (byte stream)

Question

I have a list of hex strings representing bytes, of the form "FF". I want to convert the whole list to a byte stream so I can send it over a socket (Python 3). It looks like the bytearray type would work, but I can't find any way to directly convert the list to a bytearray.

I can do it manually in a loop, but figure there must be a better Python way to do this.

Solution

hexstrings = ["DE", "AD", "BE", "EF"]   # big-endian 0xDEADBEEF

bytes = bytearray(int(x, 16) for x in hexstrings)
bytes = bytearray.fromhex("".join(hexstrings))     # Python 2.6 may need u""

If you've got a lot of 'em, it might be worthwhile to see which of those is fastest.

Comments

[Lance Roberts]

I'm looking to go the other direction.

[John Machin]

First code comment: 0xDEADBEEF is an integer which relates to hexstrings only on a bigendian machine. Second code comment: Your code works with python 2.7 without change; it would need major surgery to get it to work on earlier versions e.g. "".join([chr(int(x, 16)) for x in hexstrings]) will do the job for Python 2.1 to 2.7 inclusive.

[kindall]

The first comment was merely an opportunity to write "Ox Dead Beef" in hex, but you are technically correct -- the best kind of correct! And "big-endian ox dead beef" is arguably even funnier. :-) On the second, it was actually Python 2.6 that insisted on having a Unicode string there, but that seems to be a bug. 2.7 behaves as you state and I've changed that. (bytearray was introduced in 2.6, just for the record.)