NB: python bitwise operations are not super fast like in C. They don't get optimized down to single CPU instructions but instead are looked up like regular type methods (e.g. __str__ and __add__). An "ob[~0]" won't kill you even in a loop but don't bother translating simple math into bit-twiddling because it won't help (and might hurt if it inflates the number of operations).
import cProfile
def flipbits():
c=0
for i in range(1,400000):
b=~i
c=c+b
print c
def negnums():
c=0
for i in range(1,400000):
b=-i
c=c+b
print c
cProfile.run("flipbits()") cProfile.run("negnums()")---
Summary:
Flipping bits is tiny bit faster actually.To make negnums function produce the same result as flipbits, we need to change b=-i to b=-i-1 and this is even slower. Poke holes in my experiment please.
-1 == (1).__neg__()