Python/data_structures/hashing/double_hash.py

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2018-03-20 23:48:58 +00:00
#!/usr/bin/env python3
from .hash_table import HashTable
from number_theory.prime_numbers import next_prime, check_prime
class DoubleHash(HashTable):
"""
Hash Table example with open addressing and Double Hash
"""
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
def __hash_function_2(self, value, data):
next_prime_gt = next_prime(value % self.size_table) \
if not check_prime(value % self.size_table) else value % self.size_table #gt = bigger than
return next_prime_gt - (data % next_prime_gt)
def __hash_double_function(self, key, data, increment):
return (increment * self.__hash_function_2(key, data)) % self.size_table
def _colision_resolution(self, key, data=None):
i = 1
new_key = self.hash_function(data)
while self.values[new_key] is not None and self.values[new_key] != key:
new_key = self.__hash_double_function(key, data, i) if \
self.balanced_factor() >= self.lim_charge else None
if new_key is None: break
else: i += 1
return new_key