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K-Means From Scratch
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K-Means From Scratch

HardPython

Problem

Write a function to implement a basic K-means clustering algorithm from scratch.

Given multidimensional points, a cluster count, an iteration limit, and deterministic initial centroids, repeatedly assign each point to its nearest centroid and recompute cluster means. Use squared Euclidean distance and choose the lowest-index centroid when distances tie. If a cluster becomes empty, retain its previous centroid. Return the final centroids and each point's final cluster label.

Input and Output

points, initial_centroids, and centroids are lists of equal-length numeric lists. Return {"centroids": [...], "labels": [...]}. Labels must correspond to the returned centroids.

Constraints

  • 1 <= len(points) <= 1000
  • 1 <= k <= len(points)
  • 1 <= max_iterations <= 100
  • All points and initial centroids have the same positive dimension
  • All coordinate values are finite numbers
  • Initial centroids contains exactly k centroids

Function Signature

def k_means(points, k, max_iterations, initial_centroids):
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