相當於Java的BitSet的Python

Question

是否有一個Python類或模塊實現了與BitSet類似的結構？

Answer 1

標準庫中沒有任何東西。嘗試：

http://pypi.python.org/pypi/bitarray

Answer 2

看一看這個implementation在Python 3

的實施基本上利用了內置int類型，這是任意精度的整數類型在Python 3（其中long是Python 2的等價物）。

#! /usr/bin/env python3 

""" 
bitset.py 

Written by Geremy Condra 

Licensed under GPLv3 

Released 3 May 2009 

This module provides a simple bitset implementation 
for Python. 
""" 

from collections import Sequence 
import math 

class Bitset(Sequence): 
    """A very simple bitset implementation for Python. 

    Note that, like with normal numbers, the leftmost 
    index is the MSB, and like normal sequences, that 
    is 0. 

    Usage: 
     >>> b = Bitset(5) 
     >>> b 
     Bitset(101) 
     >>> b[:] 
     [True, False, True] 
     >>> b[0] = False 
     >>> b 
     Bitset(001) 
     >>> b << 1 
     Bitset(010) 
     >>> b >> 1 
     Bitset(000) 
     >>> b & 1 
     Bitset(001) 
     >>> b | 2 
     Bitset(011) 
     >>> b^6 
     Bitset(111) 
     >>> ~b 
     Bitset(110) 
    """ 

    value = 0 
    length = 0 

    @classmethod 
    def from_sequence(cls, seq): 
     """Iterates over the sequence to produce a new Bitset. 

     As in integers, the 0 position represents the LSB. 
     """ 
     n = 0 
     for index, value in enumerate(reversed(seq)): 
      n += 2**index * bool(int(value)) 
     b = Bitset(n) 
     return b 

    def __init__(self, value=0, length=0): 
     """Creates a Bitset with the given integer value.""" 
     self.value = value 
     try: self.length = length or math.floor(math.log(value, 2)) + 1 
     except Exception: self.length = 0 

    def __and__(self, other): 
     b = Bitset(self.value & int(other)) 
     b.length = max((self.length, b.length)) 
     return b 

    def __or__(self, other): 
     b = Bitset(self.value | int(other)) 
     b.length = max((self.length, b.length)) 
     return b 

    def __invert__(self): 
     b = Bitset(~self.value) 
     b.length = max((self.length, b.length)) 
     return b 

    def __xor__(self, value): 
     b = Bitset(self.value^int(value)) 
     b.length = max((self.length, b.length)) 
     return b 

    def __lshift__(self, value): 
     b = Bitset(self.value << int(value)) 
     b.length = max((self.length, b.length)) 
     return b 

    def __rshift__(self, value): 
     b = Bitset(self.value >> int(value)) 
     b.length = max((self.length, b.length)) 
     return b 

    def __eq__(self, other): 
     try: 
      return self.value == other.value 
     except Exception: 
      return self.value == other 

    def __int__(self): 
     return self.value 

    def __str__(self): 
     s = "" 
     for i in self[:]: 
      s += "1" if i else "0" 
     return s 

    def __repr__(self): 
     return "Bitset(%s)" % str(self) 

    def __getitem__(self, s): 
     """Gets the specified position. 

     Like normal integers, 0 represents the MSB. 
     """ 
     try: 
      start, stop, step = s.indices(len(self)) 
      results = [] 
      for position in range(start, stop, step): 
       pos = len(self) - position - 1 
       results.append(bool(self.value & (1 << pos))) 
      return results 
     except: 
      pos = len(self) - s - 1 
      return bool(self.value & (1 << pos)) 

    def __setitem__(self, s, value): 
     """Sets the specified position/s to value. 

     Like normal integers, 0 represents the MSB. 
     """ 
     try: 
      start, stop, step = s.indices(len(self)) 
      for position in range(start, stop, step): 
       pos = len(self) - position - 1 
       if value: self.value |= (1 << pos) 
       else: self.value &= ~(1 << pos) 
      maximum_position = max((start + 1, stop, len(self))) 
      self.length = maximum_position 
     except: 
      pos = len(self) - s - 1 
      if value: self.value |= (1 << pos) 
      else: self.value &= ~(1 << pos) 
      if len(self) < pos: self.length = pos 
     return self 

    def __iter__(self): 
     """Iterates over the values in the bitset.""" 
     for i in self[:]: 
      yield i 

    def __len__(self): 
     """Returns the length of the bitset.""" 
     return self.length 

Answer 3

你可能想看看一個模塊我編寫的名爲bitstring（完整文檔here），雖然需要被儘可能快的簡單情況我還是建議bitarray。

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