I've a string composed of ~75 000 bits (very long string).
I would like to create a binary file which is represented by this sequence of bits. I did the following code :
byte_array = bytearray(global_bits_str.encode())
with open('file1.bin', 'wb') as f:
f.write(byte_array)
But when I check file1.bin I can see that it's composed of 75 000 bytes instead of 75 000 bits. I guess it has been encoded in ascii (1 byte per bit) in the file.
Any suggestions ?
You can use the int builtin to convert your binary string into a sequence of integers, then pass that to bytearray.
Example for one byte:
>>> int('10101010', 2)
170
>>> bytearray([170])
bytearray(b'\xaa')
Splitting the string:
chunks = [bit_string[n:n+8] for n in range(0, len(bit_string), 8)]
You'll have to do some special casing for the last chunk since it may not be a full byte, which can be done by ljust to left-pad it with zeros.
Putting it together:
def to_bytes(bits, size=8, pad='0'):
chunks = [bits[n:n+size] for n in range(0, len(bits), size)]
if pad:
chunks[-1] = chunks[-1].ljust(size, pad)
return bytearray([int(c, 2) for c in chunks]
# Usage:
byte_array = to_bytes(global_bits_str)
