hexadecimal string to byte array in python


I have a long Hex string that represents a series of values of different types. I wish to convert this Hex String into a byte array so that I can shift each value out and convert it into its proper data type.

Asked By: Richard



A good one liner is:

byte_list = map(ord, hex_string)

This will iterate over each char in the string and run it through the ord() function. Only tested on python 2.6, not too sure about 3.0+.


Answered By: karlw

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

import binascii
b=[ord(x) for x in s]
Answered By: Bruce

You should be able to build a string holding the binary data using something like:

data = "fef0babe"
bits = ""
for x in xrange(0, len(data), 2)
  bits += chr(int(data[x:x+2], 16))

This is probably not the fastest way (many string appends), but quite simple using only core Python.

Answered By: unwind

Suppose your hex string is something like

>>> hex_string = "deadbeef"

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

>>> bytearray.fromhex(hex_string)

Convert it to a bytes object (Python 3):

>>> bytes.fromhex(hex_string)

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
Answered By: tzot

Assuming you have a byte string like so


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

import struct

bytes = 'x12x45x00xAB'
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


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

Answered By: Hovo

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.

Answered By: kugg
def hex2bin(s):
    hex_table = ['0000', '0001', '0010', '0011',
                 '0100', '0101', '0110', '0111',
                 '1000', '1001', '1010', '1011',
                 '1100', '1101', '1110', '1111']
    bits = ''
    for i in range(len(s)):
        bits += hex_table[int(s[i], base=16)]
    return bits
Answered By: Dmitry Sobolev

You can use the Codecs module in the Python Standard Library, i.e.

import codecs

codecs.decode(hexstring, 'hex_codec')
Answered By: velsim

Sometimes byte-array conversion doesn’t work so in this case you can do this:

hex_string = "deadbeef"
data = ["0x" + hex_string[i:i+2] for i in range(0,len(hex_string), 2)]
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