hashtable.py

import numpy as np
    
class HashTable:
    def __init__(self, hash_size, inp_dimensions):
        self.hash_size = hash_size
        self.inp_dimensions = inp_dimensions
        self.hash_table = dict()
        self.projections = np.random.randn(self.hash_size, inp_dimensions)
        
    def generate_hash(self, inp_vector):
        bools = (np.dot(inp_vector, self.projections.T) > 0).astype('int')
        return ''.join(bools.astype('str'))

    def __setitem__(self, inp_vec, label):
        hash_value = self.generate_hash(inp_vec)
        self.hash_table[hash_value] = self.hash_table\
            .get(hash_value, list()) + [label]
        
    def __getitem__(self, inp_vec):
        hash_value = self.generate_hash(inp_vec)
        return self.hash_table.get(hash_value, [])
        
hash_table = HashTable(hash_size=4, inp_dimensions=20)