diff --git a/machine_learning/self_organizing_map.py b/machine_learning/self_organizing_map.py new file mode 100644 index 000000000..bd3d388f9 --- /dev/null +++ b/machine_learning/self_organizing_map.py @@ -0,0 +1,73 @@ +""" +https://en.wikipedia.org/wiki/Self-organizing_map +""" +import math + + +class SelfOrganizingMap: + def get_winner(self, weights: list[list[float]], sample: list[int]) -> int: + """ + Compute the winning vector by Euclidean distance + + >>> SelfOrganizingMap().get_winner([[1, 2, 3], [4, 5, 6]], [1, 2, 3]) + 1 + """ + d0 = 0.0 + d1 = 0.0 + for i in range(len(sample)): + d0 += math.pow((sample[i] - weights[0][i]), 2) + d1 += math.pow((sample[i] - weights[1][i]), 2) + return 0 if d0 > d1 else 1 + return 0 + + def update( + self, weights: list[list[int | float]], sample: list[int], j: int, alpha: float + ) -> list[list[int | float]]: + """ + Update the winning vector. + + >>> SelfOrganizingMap().update([[1, 2, 3], [4, 5, 6]], [1, 2, 3], 1, 0.1) + [[1, 2, 3], [3.7, 4.7, 6]] + """ + for i in range(len(weights)): + weights[j][i] += alpha * (sample[i] - weights[j][i]) + return weights + + +# Driver code +def main() -> None: + # Training Examples ( m, n ) + training_samples = [[1, 1, 0, 0], [0, 0, 0, 1], [1, 0, 0, 0], [0, 0, 1, 1]] + + # weight initialization ( n, C ) + weights = [[0.2, 0.6, 0.5, 0.9], [0.8, 0.4, 0.7, 0.3]] + + # training + self_organizing_map = SelfOrganizingMap() + epochs = 3 + alpha = 0.5 + + for i in range(epochs): + for j in range(len(training_samples)): + + # training sample + sample = training_samples[j] + + # Compute the winning vector + winner = self_organizing_map.get_winner(weights, sample) + + # Update the winning vector + weights = self_organizing_map.update(weights, sample, winner, alpha) + + # classify test sample + sample = [0, 0, 0, 1] + winner = self_organizing_map.get_winner(weights, sample) + + # results + print(f"Clusters that the test sample belongs to : {winner}") + print(f"Weights that have been trained : {weights}") + + +# running the main() function +if __name__ == "__main__": + main()