classic_hopfiled.py

import numpy as np


def is_binary(x):
    if np.all(np.abs(x) == 1):
        return x
    raise AttributeError('Inputs need to be binary: 1 or -1')


class ClassicHopfield:
    def __init__(self, memories):
        self.memories = is_binary(memories)
        self.connections = self._generate_connections()

    def _generate_connections(self):
        outer_products = np.dstack([np.outer(memory) for memory in self.memories])
        stack_sum = np.sum(outer_products, axis=2)
        return np.fill_diagonal(stack_sum, 0)

    def update(self, query, n_updates=1):
        query = is_binary(query)
        interaction = np.where(self.connections @ query >= 0, 1, -1)
        for _ in range(n_updates):
            for i, unit in enumerate(query):
                interaction[i] = (-1) ** int((self.connections[i, :] @ interaction) < 0)
        return interaction