Question

我在Python中有这样的列表：[1,0,0,0,0,0,0,0]。我可以将它转换为整数，就像我输入0b10000000（即转换为128）一样吗？我还需要将[1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0]之类的序列转换为整数（这里它将返回0b1100000010000000，即259）。如果有必要，列表长度总是8的倍数。

Answer 1

您可以使用bitshifting：

out = 0
for bit in bitlist:
    out = (out << 1) | bit

这很容易击败A. R. S.提出的“int cast”方法，或者由Steven Rumbalski提出的修改后的演员阵容：

>>> def intcaststr(bitlist):
...     return int("".join(str(i) for i in bitlist), 2)
... 
>>> def intcastlookup(bitlist):
...     return int(''.join('01'[i] for i in bitlist), 2)
... 
>>> def shifting(bitlist):
...     out = 0
...     for bit in bitlist:
...         out = (out << 1) | bit
...     return out
... 
>>> timeit.timeit('convert([1,0,0,0,0,0,0,0])', 'from __main__ import intcaststr as convert', number=100000)
0.5659139156341553
>>> timeit.timeit('convert([1,0,0,0,0,0,0,0])', 'from __main__ import intcastlookup as convert', number=100000)
0.4642159938812256
>>> timeit.timeit('convert([1,0,0,0,0,0,0,0])', 'from __main__ import shifting as convert', number=100000)
0.1406559944152832

Answer 2

...或使用bitstring模块

>>> from bitstring import BitArray
>>> bitlist=[1,0,0,0,0,0,0,0]
>>> b = BitArray(bitlist)
>>> b.uint
128

Answer 3

我遇到的方法稍微优于Martijn Pieters解决方案，尽管他的解决方案当然更漂亮。我对结果感到有些惊讶，但无论如何......

import timeit

bit_list = [1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0]

def mult_and_add(bit_list):
    output = 0
    for bit in bit_list:
        output = output * 2 + bit
    return output

def shifting(bitlist):
     out = 0
     for bit in bitlist:
         out = (out << 1) | bit
     return out

n = 1000000

t1 = timeit.timeit('convert(bit_list)', 'from __main__ import mult_and_add as convert, bit_list', number=n)
print "mult and add method time is : {} ".format(t1)
t2 = timeit.timeit('convert(bit_list)', 'from __main__ import shifting as convert, bit_list', number=n)
print "shifting method time is : {} ".format(t2)

结果：

mult and add method time is : 1.69138722958 
shifting method time is : 1.94066818592

Answer 4

试试这个单行：

int("".join(str(i) for i in my_list), 2)

如果你关注速度/效率，请看看Martijn Pieters的解决方案。

Answer 5

这如何：

out = sum([b<<i for i, b in enumerate(my_list)])

或以相反的顺序：

out = sum([b<<i for i, b in enumerate(my_list[::-1])])

在Python中将位列表转换为整数

5 个答案: