e8810b73c4
## What changes were proposed in this pull request? This patch adds a `compressed` method to ML `Matrix` class, which returns the minimal storage representation of the matrix - either sparse or dense. Because the space occupied by a sparse matrix is dependent upon its layout (i.e. column major or row major), this method must consider both cases. It may also be useful to force the layout to be column or row major beforehand, so an overload is added which takes in a `columnMajor: Boolean` parameter. The compressed implementation relies upon two new abstract methods `toDense(columnMajor: Boolean)` and `toSparse(columnMajor: Boolean)`, similar to the compressed method implemented in the `Vector` class. These methods also allow the layout of the resulting matrix to be specified via the `columnMajor` parameter. More detail on the new methods is given below. ## How was this patch tested? Added many new unit tests ## New methods (summary, not exhaustive list) **Matrix trait** - `private[ml] def toDenseMatrix(columnMajor: Boolean): DenseMatrix` (abstract) - converts the matrix (either sparse or dense) to dense format - `private[ml] def toSparseMatrix(columnMajor: Boolean): SparseMatrix` (abstract) - converts the matrix (either sparse or dense) to sparse format - `def toDense: DenseMatrix = toDense(true)` - converts the matrix (either sparse or dense) to dense format in column major layout - `def toSparse: SparseMatrix = toSparse(true)` - converts the matrix (either sparse or dense) to sparse format in column major layout - `def compressed: Matrix` - finds the minimum space representation of this matrix, considering both column and row major layouts, and converts it - `def compressed(columnMajor: Boolean): Matrix` - finds the minimum space representation of this matrix considering only column OR row major, and converts it **DenseMatrix class** - `private[ml] def toDenseMatrix(columnMajor: Boolean): DenseMatrix` - converts the dense matrix to a dense matrix, optionally changing the layout (data is NOT duplicated if the layouts are the same) - `private[ml] def toSparseMatrix(columnMajor: Boolean): SparseMatrix` - converts the dense matrix to sparse matrix, using the specified layout **SparseMatrix class** - `private[ml] def toDenseMatrix(columnMajor: Boolean): DenseMatrix` - converts the sparse matrix to a dense matrix, using the specified layout - `private[ml] def toSparseMatrix(columnMajors: Boolean): SparseMatrix` - converts the sparse matrix to sparse matrix. If the sparse matrix contains any explicit zeros, they are removed. If the layout requested does not match the current layout, data is copied to a new representation. If the layouts match and no explicit zeros exist, the current matrix is returned. Author: sethah <seth.hendrickson16@gmail.com> Closes #15628 from sethah/matrix_compress. |
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Apache Spark
Spark is a fast and general cluster computing system for Big Data. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Spark Streaming for stream processing.
Online Documentation
You can find the latest Spark documentation, including a programming guide, on the project web page. This README file only contains basic setup instructions.
Building Spark
Spark is built using Apache Maven. To build Spark and its example programs, run:
build/mvn -DskipTests clean package
(You do not need to do this if you downloaded a pre-built package.)
You can build Spark using more than one thread by using the -T option with Maven, see "Parallel builds in Maven 3". More detailed documentation is available from the project site, at "Building Spark".
For general development tips, including info on developing Spark using an IDE, see "Useful Developer Tools".
Interactive Scala Shell
The easiest way to start using Spark is through the Scala shell:
./bin/spark-shell
Try the following command, which should return 1000:
scala> sc.parallelize(1 to 1000).count()
Interactive Python Shell
Alternatively, if you prefer Python, you can use the Python shell:
./bin/pyspark
And run the following command, which should also return 1000:
>>> sc.parallelize(range(1000)).count()
Example Programs
Spark also comes with several sample programs in the examples directory.
To run one of them, use ./bin/run-example <class> [params]. For example:
./bin/run-example SparkPi
will run the Pi example locally.
You can set the MASTER environment variable when running examples to submit
examples to a cluster. This can be a mesos:// or spark:// URL,
"yarn" to run on YARN, and "local" to run
locally with one thread, or "local[N]" to run locally with N threads. You
can also use an abbreviated class name if the class is in the examples
package. For instance:
MASTER=spark://host:7077 ./bin/run-example SparkPi
Many of the example programs print usage help if no params are given.
Running Tests
Testing first requires building Spark. Once Spark is built, tests can be run using:
./dev/run-tests
Please see the guidance on how to run tests for a module, or individual tests.
A Note About Hadoop Versions
Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported storage systems. Because the protocols have changed in different versions of Hadoop, you must build Spark against the same version that your cluster runs.
Please refer to the build documentation at "Specifying the Hadoop Version" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions.
Configuration
Please refer to the Configuration Guide in the online documentation for an overview on how to configure Spark.
## Contributing
Please review the Contribution to Spark guide for information on how to get started contributing to the project.