Machine Learning Library (MLlib) Guide
MLlib is Spark’s machine learning (ML) library. Its goal is to make practical machine learning scalable and easy. At a high level, it provides tools such as:
- ML Algorithms: common learning algorithms such as classification, regression, clustering, and collaborative filtering
- Featurization: feature extraction, transformation, dimensionality reduction, and selection
- Pipelines: tools for constructing, evaluating, and tuning ML Pipelines
- Persistence: saving and load algorithms, models, and Pipelines
- Utilities: linear algebra, statistics, data handling, etc.
Announcement: DataFrame-based API is primary API
The MLlib RDD-based API is now in maintenance mode.
What are the implications?
- MLlib will still support the RDD-based API in
spark.mllibwith bug fixes.
- MLlib will not add new features to the RDD-based API.
- In the Spark 2.x releases, MLlib will add features to the DataFrames-based API to reach feature parity with the RDD-based API.
Why is MLlib switching to the DataFrame-based API?
- DataFrames provide a more user-friendly API than RDDs. The many benefits of DataFrames include Spark Datasources, SQL/DataFrame queries, Tungsten and Catalyst optimizations, and uniform APIs across languages.
- The DataFrame-based API for MLlib provides a uniform API across ML algorithms and across multiple languages.
- DataFrames facilitate practical ML Pipelines, particularly feature transformations. See the Pipelines guide for details.
What is “Spark ML”?
- “Spark ML” is not an official name but occasionally used to refer to the MLlib DataFrame-based API.
This is majorly due to the
org.apache.spark.mlScala package name used by the DataFrame-based API, and the “Spark ML Pipelines” term we used initially to emphasize the pipeline concept.
Is MLlib deprecated?
- No. MLlib includes both the RDD-based API and the DataFrame-based API. The RDD-based API is now in maintenance mode. But neither API is deprecated, nor MLlib as a whole.
MLlib uses the linear algebra package Breeze, which depends on netlib-java for optimised numerical processing. If native libraries1 are not available at runtime, you will see a warning message and a pure JVM implementation will be used instead.
Due to licensing issues with runtime proprietary binaries, we do not include
proxies by default.
netlib-java / Breeze to use system optimised binaries, include
com.github.fommil.netlib:all:1.1.2 (or build Spark with
-Pnetlib-lgpl) as a dependency of your
project and read the netlib-java documentation for your
platform’s additional installation instructions.
Configuring these BLAS implementations to use a single thread for operations may actually improve performance (see SPARK-21305). It is usually optimal to match this to the number of cores each Spark task is configured to use, which is 1 by default and typically left at 1.
Please refer to resources like the following to understand how to configure the number of threads these BLAS implementations use: Intel MKL or Intel oneMKL and OpenBLAS. Note that if nativeBLAS is not properly configured in system, java implementation(f2jBLAS) will be used as fallback option.
To use MLlib in Python, you will need NumPy version 1.4 or newer.
Highlights in 3.0
The list below highlights some of the new features and enhancements added to MLlib in the
release of Spark:
- Multiple columns support was added to
StopWordsRemover(SPARK-29808) and PySpark
- Tree-Based Feature Transformation was added (SPARK-13677).
- Two new evaluators
RankingEvaluator(SPARK-28045) were added.
- Sample weights support was added in
- R API for
PowerIterationClusteringwas added (SPARK-19827).
- Added Spark ML listener for tracking ML pipeline status (SPARK-23674).
- Fit with validation set was added to Gradient Boosted Trees in Python (SPARK-24333).
RobustScalertransformer was added (SPARK-28399).
Factorization Machinesclassifier and regressor were added (SPARK-29224).
- Gaussian Naive Bayes Classifier (SPARK-16872) and Complement Naive Bayes Classifier (SPARK-29942) were added.
- ML function parity between Scala and Python (SPARK-28958).
predictRawis made public in all the Classification models.
predictProbabilityis made public in all the Classification models except
The migration guide is now archived on this page.