How to create an array of bits in Python?

Question:

How can I declare a bit array of a very large size, say 6 million bits?

Asked By: zheric

||

Answers:

from bitarray import bitarray

a = bitarray(2**20)

You can check out more info about this module at http://pypi.python.org/pypi/bitarray/

Answered By: SJP

The bitstring module may help:

from bitstring import BitArray
a = BitArray(6000000)

This will take less than a megabyte of memory, and it’s easy to set, read, slice and interpret bits. Unlike the bitarray module it’s pure Python, plus it works for Python 3.

See the documentation for more details.

Answered By: Scott Griffiths

Get the bitarray module using

pip install bitarray

Then, this code will create a bit array of size 6 million,

from bitarray import bitarray
bit_array = bitarray(6000000)

You can initialize all the bits to zero using

bit_array.setall(0)

To set a particular bit, say bit number 25, to 1, do this:

bit_array[25]=1   
Answered By: Tarun

This one-liner converts bytes to a list of True/False bit values. Might be not performant for 6M bits but for small flags it should be fine and does not need additional dependencies.

>>> flags = bytes.fromhex(b"beef")
>>> bits =  [flags[i//8] & 1 << i%8 != 0 for i in range(len(flags) * 8)]
>>> print(bits)
[False, True, True, True, True, True, False, True, True, True, True, True, False, True, True, True]
Answered By: Felix Weis

Quite easily

bitarray60000 = 1<<60000

With that, you can use bitshift operator to your heart content.
For instance, position 2 set True would be:

bitarray60000 | 1<<2

Getting bit from position 2

bitarray60000 & 1<<2

I guess the idea is quite simple. Though some operations might be tricky.

Answered By: Pavel Hanpari
Categories: questions Tags: , ,
Answers are sorted by their score. The answer accepted by the question owner as the best is marked with
at the top-right corner.