The built-in hash function differs from Python2.5 to Python2.7.
If you are planning to migrate from Python 2.5 to Python 2.7 and
you were dumb enough to store the value of python 2.5's hash
function, just like I did, you might be interested in the following
code snippet.
This is the hash function that Google uses in production for python 2.5:
def c_mul(a, b):
return eval(hex((long(a) * b) & 0xFFFFFFFFFFFFFFFFL)[:-1])
def py25hash(self):
if not self:
return 0 # empty
value = ord(self[0]) << 7
for char in self:
value = c_mul(1000003, value) ^ ord(char)
value = value ^ len(self)
if value == -1:
value = -2
return value
I wonder why Google is not using 64bit hashes in Python 2.7
Cheers,
-Andrin
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