hash_index_hash_function.py

class HashIndex(object):
	def __init__(self, data: List, col: str) -> None:
		""" Init the hash index class

		Params:
			data (list) - Our data as a list of dicts
			col (str) - The column (dict key) to create an index on
		"""
		self.table = data
		self.on = col

		self.create_hash_index()

	def hash_function(self, key: int) -> tuple:
		""" A hash function that generates a simple hash of our key, and a bucket value

		Params:
			key (int)- The value of the column we want to hash

		Returns:
			a_hash (int) - A hash of the key
			bucket_no (int) - The bucket number to insert the value
		"""
		buckets = 97 # An arbitrary number of buckets

		# Generate a hash (square the number twice then extract 4 chars )
		keyy = key ** 2 ** 2
		a_hash = int(str(keyy)[1:5])

		# Get the bucket number
		bucket_no = a_hash % buckets

		return a_hash, bucket_no