How to output string of bits as a binary file in python

Question

I have a string of bits I would like to output as a binary file.

s = '10101010'

The string can be much longer or complex than the example above however a shorter one illustrates the point more clearly.

I want to output this so the binary representation of the new file would be 10101010 rather than the string equivalent however I have no idea how best to do this and any help would be appreciated.

Thanks

In other words, you want the file to contain a single byte of value 170? Can we assume that the string will always contain a multiple of 8 characters? If not, where should the boundaries between bytes be drawn? — Tim Pietzcker
– Tim Pietzcker, Commented Feb 22, 2015 at 16:18

Marcus Müller · Accepted Answer · 2015-02-22 16:24:14Z

2

What you'd want is to split your string to 8-bit-chunks, and then convert them to bytes individually:

for index in range(len(s)/8):
    substring = s[index * 8: index*8 + 8]
    byteval = int(substring, base=2)
    print chr(byteval)

answered Feb 22, 2015 at 16:24

Marcus Müller

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2 Comments

Karoly Horvath Over a year ago

''.join([chr(int(s[index * 8: index*8 + 8], base=2)) for index in range(len(s)/8)])

Marcus Müller Over a year ago

@KarolyHorvath: nice list comprehension; definitively faster. My code was a bit on the verbatim side to illustrate the usage of int() for OP.

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