Github user viirya commented on a diff in the pull request: https://github.com/apache/spark/pull/15018#discussion_r95775162 --- Diff: mllib/src/main/scala/org/apache/spark/mllib/regression/IsotonicRegression.scala --- @@ -312,10 +313,19 @@ class IsotonicRegression private (private var isotonic: Boolean) extends Seriali } /** - * Performs a pool adjacent violators algorithm (PAV). - * Uses approach with single processing of data where violators - * in previously processed data created by pooling are fixed immediately. - * Uses optimization of discovering monotonicity violating sequences (blocks). + * Performs a pool adjacent violators algorithm (PAV). Implements the algorithm originally + * described in [1], using the formulation from [2, 3]. Uses an array to keep track of start + * and end indices of blocks. + * + * [1] Grotzinger, S. J., and C. Witzgall. "Projections onto order simplexes." Applied + * mathematics and Optimization 12.1 (1984): 247-270. + * + * [2] Best, Michael J., and Nilotpal Chakravarti. "Active set algorithms for isotonic + * regression; a unifying framework." Mathematical Programming 47.1-3 (1990): 425-439. + * + * [3] Best, Michael J., Nilotpal Chakravarti, and Vasant A. Ubhaya. "Minimizing separable convex + * functions subject to simple chain constraints." SIAM Journal on Optimization 10.3 (2000): + * 658-672. * * @param input Input data of tuples (label, feature, weight). --- End diff -- Can you update the param doc to indicate that now negative weights are prohibited?
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