How to Efficiently Convert Between Binary and ASCII in Python?

Converting Between Binary and ASCII

The provided code converts a string to binary using a reduction lambda function. However, the method for converting binary back to ASCII is not immediately apparent.

Python 2 (For ASCII Characters)

For ASCII characters in the range [ -~], Python 2 offers an easy solution:

import binascii
bin(int(binascii.hexlify('hello'), 16))
# Output: '0b110100001100101011011000110110001101111'

To reverse the process:

n = int('0b110100001100101011011000110110001101111', 2)
binascii.unhexlify('%x' % n)
# Output: 'hello'

Python 3 (All Unicode Characters)

Python 3 introduced support for all Unicode characters. The following functions provide a unified conversion interface:

def text_to_bits(text):
    bits = bin(int.from_bytes(text.encode(), 'big'))[2:]
    return bits.zfill(8 * ((len(bits) + 7) // 8))

def text_from_bits(bits):
    n = int(bits, 2)
    return n.to_bytes((n.bit_length() + 7) // 8, 'big').decode()

Unicode-Aware Conversion

Finally, for Python 2 and 3 compatibility, here's a single-source code snippet that handles Unicode conversion:

def text_to_bits(text):
    bits = bin(int(binascii.hexlify(text.encode()), 16))[2:]
    return bits.zfill(8 * ((len(bits) + 7) // 8))

def text_from_bits(bits):
    n = int(bits, 2)
    return int2bytes(n).decode()

def int2bytes(i):
    hex_string = '%x' % i
    n = len(hex_string)
    return binascii.unhexlify(hex_string.zfill(n + (n & 1)))

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