Convert bytes to bits in python

Question

I am working with Python3 2  I need to take a hex stream as an input and parse it at bit-level  So I used   bytes fromhex input str   to convert the string to actual bytes  Now how do I convert these bytes to bits

User · Answer

Operations are much faster when you work at the integer level. In particular, converting to a string as suggested here is really slow.

If you want bit 7 and 8 only, use e.g.

val = (byte >> 6) & 3

(this is: shift the byte 6 bits to the right - dropping them. Then keep only the last two bits 3 is the number with the first two bits set...)

These can easily be translated into simple CPU operations that are super fast.

User · Answer

Another way to do this is by using the bitstring module    gt  gt  gt  from bitstring import BitArray  gt  gt  gt  input str    0xff   gt  gt  gt  c   BitArray hex input str   gt  gt  gt  c bin  0b11111111    And if you need to strip the leading 0b    gt  gt  gt  c bin 2    11111111    The bitstring module isn t a requirement  as jcollado s answer shows  but it has lots of performant methods for turning input into bits and manipulating them  You might find this handy  or not   for example    gt  gt  gt  c uint 255  gt  gt  gt  c invert    gt  gt  gt  c bin 2    00000000    etc

User · Answer

input str    quot ABC quot   bin byte  for byte in bytes input str   quot utf-8 quot     Will give    0b1000001    0b1000010    0b1000011

User · Answer

Here how to do it using  format     print  bin signedDate         join format x   08b   for x in bytevector       It is important the 08b   That means it will be a maximum of 8 leading zeros be appended to complete a byte  If you don t specify this then the format will just have a variable bit length for each converted byte

User · Answer

To binary   bin byte  2   zfill 8

User · Answer

using python format string syntax   gt  gt  gt  mybyte   bytes fromhex  0F     create my byte using a hex string  gt  gt  gt  binary string      08b   format int mybyte hex   16    gt  gt  gt  print binary string  00001111   The second line is where the magic happens  All byte objects have a  hex   function  which returns a hex string  Using this hex string  we convert it to an integer  telling the int   function that it s a base 16 string  because hex is base 16   Then we apply formatting to that integer so it displays as a binary string  The   08b  is where the real magic happens  It is using the Format Specification Mini-Language format spec  Specifically it s using the width and the type parts of the format spec syntax  The 8 sets width to 8  which is how we get the nice 0000 padding  and the b sets the type to binary   I prefer this method over the bin   method because using a format string gives a lot more flexibility

User · Answer

I think simplest would be use numpy here  For example you can read a file as bytes and then expand it to bits easily like this   Bytes   numpy fromfile filename  dtype    uint8   Bits   numpy unpackbits Bytes

User · Answer

Use ord when reading reading bytes   byte binary   bin ord f read 1      Add  2   to remove the  0b  prefix   Or  Using str format        08b   format ord f read 1

User · Answer

The other answers here provide the bits in big-endian order    x01  becomes  00000001    In case you re interested in little-endian order of bits  which is useful in many cases  like common representations of bignums etc - here s a snippet for that   def bits little endian from bytes s       return    join bin ord x   2   rjust 8  0     -1  for x in s    And for the other direction   def bytes from bits little endian s       return    join chr int s i i 8    -1   2   for i in range 0  len s   8

User · Answer

What about something like this    gt  gt  gt  bin int  ff   base 16    0b11111111    This will convert the hexadecimal string you have to an integer and that integer to a string in which each byte is set to 0 1 depending on the bit-value of the integer   As pointed out by a comment  if you need to get rid of the 0b prefix  you can do it this way    gt  gt  gt  bin int  ff   base 16   lstrip  0b    11111111    or this way    gt  gt  gt  bin int  ff   base 16   2    11111111

[python] Convert bytes to bits in python

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