kmeans.py

import numpy as np
from numpy.linalg import norm


class Kmeans:
    '''Implementing Kmeans algorithm.'''

    def __init__(self, n_clusters, max_iter=100, random_state=123):
        self.n_clusters = n_clusters
        self.max_iter = max_iter
        self.random_state = random_state

    def initializ_centroids(self, X):
        np.random.RandomState(self.random_state)
        random_idx = np.random.permutation(X.shape[0])
        centroids = X[random_idx[:self.n_clusters]]
        return centroids

    def compute_centroids(self, X, labels):
        centroids = np.zeros((self.n_clusters, X.shape[1]))
        for k in range(self.n_clusters):
            centroids[k, :] = np.mean(X[labels == k, :], axis=0)
        return centroids

    def compute_distance(self, X, centroids):
        distance = np.zeros((X.shape[0], self.n_clusters))
        for k in range(self.n_clusters):
            row_norm = norm(X - centroids[k, :], axis=1)
            distance[:, k] = np.square(row_norm)
        return distance

    def find_closest_cluster(self, distance):
        return np.argmin(distance, axis=1)

    def compute_sse(self, X, labels, centroids):
        distance = np.zeros(X.shape[0])
        for k in range(self.n_clusters):
            distance[labels == k] = norm(X[labels == k] - centroids[k], axis=1)
        return np.sum(np.square(distance))
    
    def fit(self, X):
        self.centroids = self.initializ_centroids(X)
        for i in range(self.max_iter):
            old_centroids = self.centroids
            distance = self.compute_distance(X, old_centroids)
            self.labels = self.find_closest_cluster(distance)
            self.centroids = self.compute_centroids(X, self.labels)
            if np.all(old_centroids == self.centroids):
                break
        self.error = self.compute_sse(X, self.labels, self.centroids)
    
    def predict(self, X):
        distance = self.compute_distance(X, self.centroids)
        return self.find_closest_cluster(distance)

At line#53 ,we are getting the error 'undefined name old_centroids'

At line#53 ,we are getting the error 'undefined name old_centroids'

I got the same error. I guess we should change old_centroids to 'self.centroids'.

Thanks for the catch! Yes, it should be self.centroids. I'll fix it shortly.

Thanks for the catch! Yes, it should be self.centroids. I'll fix it shortly.

You're welcome!