Convert Python str/unicode object to binary/hex blob

Question

Is there an easy way to get some str/unicode object represented as a big binary number (or an hex one)?

I've been reading some answers to related questions but none of them works for my scenario.

I tried using the struct module from the STL but it didn't work as expected. Chars, like in binary files are displayed as, well chars.

Am I trying something impossible?

Example:

def strbin(inp):
    # sorcery!
    return out

>> print strbin("hello")
# Any of these is cool (outputs are random keystrokes)
0b1001010101010000111001110001...
0xad9f...

Are you trying to get an integer or a string of the hex/binary representation? In your example you have integers given as binary and hex literals. — Peter Graham
– Peter Graham, Commented Jul 18, 2011 at 2:20
@Peter, in most of the use scenarios I'm thinking of I would say an integer. This is just for some silly compression algorithm I thought some days ago, just for fun. — toqueteos
– toqueteos, Commented Jul 18, 2011 at 2:53

senderle · Accepted Answer · 2011-07-18 02:10:53Z

20

You could try bitarray:

>>> import bitarray
>>> b = bitarray.bitarray()
>>> b.fromstring('a')
>>> b
bitarray('01100001')
>>> b.to01()
'01100001'
>>> b.fromstring('pples')
>>> b.tostring()
'apples'
>>> b.to01()
'011000010111000001110000011011000110010101110011'

answered Jul 18, 2011 at 2:10

senderle

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4 Comments

toqueteos Over a year ago

I can't give you and upvote senderle (still 4 reputation left for that) but your answer is what I was looking for. Checking this as accepted answer :) Thank you so much.

senderle Over a year ago

I'll also mention bitstring, which I think is a tad bit more versatile, but it's pure Python, so it's slower.

toqueteos Over a year ago

There's no STL library that could this without some sorcery right? Just curious. Edit: Oh and you got the upboat.

senderle Over a year ago

@ratnushock, well, once you have an int, you could call bin on it. But that doesn't pad the byte, so it doesn't concatenate well. (hex doesn't pad either; hex(5) returns '0x5'.) JBernardo's answer gets the padding right and is as good as anything I can think of from the standard libraries.

JBernardo · Accepted Answer · 2011-07-18 02:35:54Z

7

Quite simple and don't require modules from pypi:

def strbin(s):
    return ''.join(format(ord(i),'0>8b') for i in s)

You'll need Python 2.6+ to use that.

answered Jul 18, 2011 at 2:35

JBernardo

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2 Comments

toqueteos Over a year ago

Well I'm pretty sure that @senderle 's answer is gonna be faster just because it's a C extension but hey STL solutions are also great. Thanks for your answer!

JBernardo Over a year ago

Probably you don't need it to be that fast. Otherwise why would you write in Python at all? Quoting the Zen: Simple is better than complex

Ravi · Accepted Answer · 2011-07-18 03:10:14Z

1

def strhex(str):
    h=""
    for x in str:
        h=h+(hex(ord(x)))[2:]
    return "0x"+h

edited Jul 18, 2011 at 3:10

answered Jul 18, 2011 at 2:22

Ravi

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2 Comments

toqueteos Over a year ago

This returns the ASCII number not the binary repr but it works in a similar way so.. Thanks for your answer!

Ravi Over a year ago

Don't the above answers also return ASCII? If you need an int, you could add int(h,16) at the end.

agf · Accepted Answer · 2011-07-18 03:32:22Z

1

A slice from a larger pretty print function I wrote that prints the ascii code in hex. Just a more Pythonic version of the previous answer's function. Also, it works properly for characters with single digit ascii codes.

def strhex(string, start = '0x'):
    return start + ''.join(('{:x}'.format(ord(char))).zfill(2) for char in string)

answered Jul 18, 2011 at 3:32

agf

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Comments

Community · Accepted Answer · 2017-05-23 12:01:49Z

1

This is basically Ravi's answer but with a tiny bugfix, so all credit to him, but the consensus among reviewers was that this was too big of a change to just do an edit and should be a separate answer instead... No idea why.

def strhex(str):
    h=""
    for x in str:
        h=h+("0" + (hex(ord(x)))[2:])[-2:]
    return "0x"+h

The difference is that in line 4, you have to check if the character is less than 0x10 and in that case prepend a zero, otherwise e.g. 0x1101 becomes 0x111.

edited May 23, 2017 at 12:01

CommunityBot

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answered Nov 17, 2015 at 17:42

FrederikVds

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