Python write string of bytes to file

Map to a bytearray() or bytes() object, then write that to the file:

with open(outputfilename, 'wb') as output:
    output.write(bytearray(int(i, 16) for i in yoursequence))

Another option is to use the binascii.unhexlify() function to turn your hex strings into a bytes value:

from binascii import unhexlify

with open(outputfilename, 'wb') as output:
    output.write(unhexlify(''.join(format(i[2:], '>02s') for i in b)))

Here we have to chop off the 0x part first, then reformat the value to pad it with zeros and join the whole into one string.

In Python 3.X, bytes() will turn an integer sequence into a bytes sequence:

>>> bytes([1,65,2,255])
b'\x01A\x02\xff'

A generator expression can be used to convert your sequence into integers (note that int(x,0) converts a string to an integer according to its prefix. 0x selects hex):

>>> list(int(x,0) for x in ['0x28','0x0','0x0','0x0'])
[40, 0, 0, 0]

Combining them:

>>> bytes(int(x,0) for x in ['0x28','0x0','0x0','0x0'])
b'(\x00\x00\x00'

And writing them out:

>>> L = ['0x28','0x0','0x0','0x0']
>>> with open('out.dat','wb') as f:
...  f.write(bytes(int(x,0) for x in L))
...
4