Dimensionality Reduction with Spark - Machine Learning with Spark - page 310

Training a dimensionality reduction model
Dimensionality reduction models in MLlib require vectors as inputs. However, unlike clus-
tering that operated on an RDD[Vector] , PCA and SVD computations are provided as
methods on a distributed RowMatrix (this difference is largely down to syntax, as a
RowMatrix is simply a wrapper around an RDD[Vector] ).