oligofren oligofren - 1 month ago 8
Python Question

How do I represent and work with n-bit vectors in Python?

In an assignment I am currently working on we need to work with bit vectors, but I am very unsure of how to do this in Python. They should be able to be from 4 bits to 20 bits. I have never worked with bit vector before, but I guess that one would one create arrays of unsigned bytes that you manipulated using the usual AND/OR/XOR operations.

The important restriction here is: I cannot rely on any libraries other than those supplied with standard Python.

I think I know how I would do this in C using arrays of 8 bit unsigned bytes:
e.g. to turn the 18th bit of a zeroed array into a one, I would do something like
my_bit_array[3] &= 1<<2

But since Python is dynamically typed and does not have a built-in array type, how would I go about doing this in a pythonic way?

And is it possible (how?) to express a bit vector of size 20? I am thinking of perhaps making a 24 bit / 3 byte vector and ignoring the 4 bits.

Answer

The library BitVector is a pure-Python library for this purpose, and should suit the needs you specified.