ECVQ implementation in Python
[1] Chou, Philip A., Tom Lookabaugh, and Robert M. Gray. "Entropy-constrained vector quantization." IEEE Transactions on Acoustics, Speech, and Signal Processing 37.1 (1989): 31-42.
[2] Arthur, David, and Sergei Vassilvitskii. "k-means++: The advantages of careful seeding." Proceedings of the eighteenth annual ACM-SIAM symposium on Discrete algorithms. Society for Industrial and Applied Mathematics, 2007.