python实现bitmap数据结构详解

class Bitmap(object):
def __init__(self, max):
self.size = self.calcElemIndex(max, True)
self.array = [0 for i in range(self.size)]

def calcElemIndex(self, num, up=False):
'''up为True则为向上取整, 否则为向下取整'''
if up:
return int((num + 31 - 1) / 31) #向上取整
return num / 31

def calcBitIndex(self, num):
return num % 31

def set(self, num):
elemIndex = self.calcElemIndex(num)
byteIndex = self.calcBitIndex(num)
elem = self.array[elemIndex]
self.array[elemIndex] = elem | (1 << byteIndex)

def clean(self, i):
elemIndex = self.calcElemIndex(i)
byteIndex = self.calcBitIndex(i)
elem = self.array[elemIndex]
self.array[elemIndex] = elem & (~(1 << byteIndex))

def test(self, i):
elemIndex = self.calcElemIndex(i)
byteIndex = self.calcBitIndex(i)
if self.array[elemIndex] & (1 << byteIndex):
return True
return False

if __name__ == '__main__':
MAX = 879
suffle_array = [45, 2, 78, 35, 67, 90, 879, 0, 340, 123, 46]
result = []
bitmap = Bitmap(MAX)
for num in suffle_array:
bitmap.set(num)

for i in range(MAX + 1):
if bitmap.test(i):
result.append(i)

print '原始数组为: %s' % suffle_array
print '排序后的数组为: %s' % result

bitmap实现了，则利用其进行排序就非常简单了。其它语言也同样可以实现bitmap，但对于静态类型语言来说，比如C/Golang这样的语言，因为可以直接声明无符号整型，所以可用位就变成32位，只需将上述代码中的31改成32即可，这点请大家注意。