Sketching Data with T-Digest In Apache Spark

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Algorithms for sketching probability distributions from large data sets are a fundamental building block of modern data science. Sketching plays a role in diverse applications ranging from visualization, optimizing data encodings, estimating quantiles, data synthesis and imputation. The T-Digest is a versatile sketching data structure. It operates on any numeric data, models tricky distribution tails with high fidelity, and most crucially it works smoothly with aggregators and map-reduce.
T-Digest is a perfect fit for Apache Spark; it is single-pass and intermediate results can be aggregated across partitions in batch jobs or aggregated across windows in streaming jobs. In this talk I will describe a native Scala implementation of the T-Digest sketching algorithm and demonstrate its use in Spark applications for visualization, quantile estimations and data synthesis.

Attendees of this talk will leave with an understanding of data sketching with T-Digest sketches, and insights about how to apply T-Digest to their own data analysis applications.

About Erik Erlandson

Erik Erlandson is a Software Engineer at Red Hat, where he investigates analytics use cases and scalable deployments for Apache Spark in the cloud. He also consults on internal data science and analytics projects. Erik is a contributor to Apache Spark and other open source projects in the Spark ecosystem, including the Spark on Kubernetes community project, Algebird and Scala.