BitVector 2.0

A pure-Python memory-efficient packed representation for bit arrays

This class presents a pure-Python memory efficient packed representation for bit arrays.

Version 2.0 provides much additional functionality that was requested by folks in the data mining community. The class now includes faster methods for counting bits, for finding the position of the next set bit, for calculating the rank of a bit, for determining the Jaccard and Hamming distances, etc. Also included in the new version are methods that should prove useful to folks who play with cryptography algorithms. There is now a method that calculates the greatest common divisor of two bit vectors and a method that finds the multiplicative inverse of a bit vector vis-a-vis a given modulus.

The class supports the following operators/methods:

__getitem__

__setitem__

__len__

__getslice__

__str__

__iter__

__contains__

__int__

__add__

__eq__, __ne__, __lt__, __le__, __gt__, __ge__

‘|’ for bitwise or

‘&’ for bitwise and

‘^’ for bitwise xor

‘~’ for bitwise inversion

‘<<’ for circular shift to the left

‘>>’ for circular shift to the right

‘+’ for concatenation

intValue(), __int__ for returning the integer value

divide_into_two

permute

unpermute

pad_from_left

pad_from_right

read_bits_from_file

write_to_file

read_bits_from_fileobject

write_bits_to_fileobject

slice assignment

reset

setValue

count_bits

count_bit_sparse

jaccard_similarity

jaccard_distance

hamming_distance

next_set_bit

rank_of_bit_set_at_index

isPowerOf2

isPowerOf2_sparse

reverse

gcd

multiplicative_inverse