godavemon 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.
...
What about letting the bits count themselves in a parallel adding scheme:
def hamming(i, j):
i ^= j
i = ((i&04444444444)>>2)+((i&022222222222)>>1)+(i&011111111111)
i = ((i&07070707070)>>3)+(i&030707070707)
return int(i%63)
This should work for 32-bit integers as from Python 2.4. For earlier Pythons the
result of i^j must be positive, effectively limiting i and j to 31 bit integers.
I didn't do any speed comparisons with other methods.
Hans
--
http://mail.python.org/mailman/listinfo/python-list
