On Jun 20, 9:27 am, godavemon <[EMAIL PROTECTED]> wrote: > I need to calculate the Hamming Distance of two integers. The hamming > distance is the number of bits in two integers that don't match. I > thought there'd be a function in math or scipy but i haven't been able > to find one. This is my function but it seems like there should be a > faster way. I do this computation many times and speed up is > important. > > def hamdist( a, b , bits = 32): > def _hamdist( x, bits): > if bits: > return (x & 1) + _hamdist(x >> 1, bits-1) > return x & 1 > return _hamdist( a ^ b, bits) > > Another alternative would be to convert the XOR to a binary string and
Isn't it a "binary string" already? > count the # of 1's. My guess is that counting the 1-bits in (a ^ b) would be hard to beat, and that a recursive function is just not in the race. > > Which would be fastest? Implement both and time them. > Are there better alternatives? I doubt it. BTW one presumes that your integers are non-negative ... HTH Cheers, John -- http://mail.python.org/mailman/listinfo/python-list
