hexadecimal string to byte array in python

Suppose your hex string is something like

>>> hex_string = "deadbeef"

Convert it to a bytearray (Python 3 and 2.7):

>>> bytearray.fromhex(hex_string)
bytearray(b'\xde\xad\xbe\xef')

Convert it to a bytes object (Python 3):

>>> bytes.fromhex(hex_string)
b'\xde\xad\xbe\xef'

Note that bytes is an immutable version of bytearray.

Convert it to a string (Python ≤ 2.7):

>>> hex_data = hex_string.decode("hex")
>>> hex_data
"\xde\xad\xbe\xef"

There is a built-in function in bytearray that does what you intend.

bytearray.fromhex("de ad be ef 00")

It returns a bytearray and it reads hex strings with or without space separator.

provided I understood correctly, you should look for binascii.unhexlify

import binascii
a='45222e'
s=binascii.unhexlify(a)
b=[ord(x) for x in s]

Assuming you have a byte string like so

"\x12\x45\x00\xAB"

and you know the amount of bytes and their type you can also use this approach

import struct

bytes = '\x12\x45\x00\xAB'
val = struct.unpack('<BBH', bytes)

#val = (18, 69, 43776)

As I specified little endian (using the '<' char) at the start of the format string the function returned the decimal equivalent.

0x12 = 18

0x45 = 69

0xAB00 = 43776

B is equal to one byte (8 bit) unsigned

H is equal to two bytes (16 bit) unsigned

More available characters and byte sizes can be found here

The advantages are..

You can specify more than one byte and the endian of the values

Disadvantages..

You really need to know the type and length of data your dealing with