The KPCA Procedure

PROC KPCA Statement

  • PROC KPCA <options>;

The PROC KPCA statement invokes the procedure. Table 1 summarizes the options available in the PROC KPCA statement.

Table 1: PROC KPCA Statement Options

Option Description
Input Data Table Option
DATA= Specifies the input data table
KPCA Options
CENTER Centers the input data
METHOD= Specifies the method of performing KPCA
NTHREADS= Specifies the number of threads to use on each computation node
RANKTHRESHOLD= Specifies the epsilon value to determine the rank of the kernel matrix
SCALE Scales the input data
Output Table Options
CENTROIDS= Specifies the name of the centroids output table
EIGENVAL= Specifies the name of the eigenvalue output table
EIGENVEC= Specifies the name of the eigenvector output table


You can specify the following options:

CENTER

centers the observations by the mean of each column.

CENTROIDS=CAS-libref.data-table

specifies the name of the output table for the centroids that are generated by clustering. This table is generated if METHOD=APPROXIMATE.

CAS-libref.data-table is a two-level name, where CAS-libref refers to the caslib and session identifier, and data-table specifies the name of the output data table. For more information about this two-level name, see the DATA= option and the section Using CAS Sessions and CAS Engine Librefs.

DATA=CAS-libref.data-table

names the input data table for PROC KPCA to use. The default is the most recently created data table. CAS-libref.data-table is a two-level name, where

CAS-libref

refers to a collection of information that is defined in the LIBNAME statement and includes the caslib, which includes a path to the data, and a session identifier, which defaults to the active session but which can be explicitly defined in the LIBNAME statement. For more information about CAS-libref, see the section Using CAS Sessions and CAS Engine Librefs.

data-table

specifies the name of the input data table.

EIGENVAL=CAS-libref.data-table

specifies the name of the output table that contains the eigenvalues.

CAS-libref.data-table is a two-level name, where CAS-libref refers to the caslib and session identifier, and data-table specifies the name of the output data table. For more information about this two-level name, see the DATA= option and the section Using CAS Sessions and CAS Engine Librefs.

EIGENVEC=CAS-libref.data-table

specifies the name of the output table that contains the eigenvectors.

CAS-libref.data-table is a two-level name, where CAS-libref refers to the caslib and session identifier, and data-table specifies the name of the output data table. For more information about this two-level name, see the DATA= option and the section Using CAS Sessions and CAS Engine Librefs.

METHOD=APPROXIMATE | EXACT

specifies the method to use in performing KPCA. You can specify the following values:

APPROXIMATE

uses the low-rank approximation method.

EXACT

uses the exact method.

By default, METHOD=APPROXIMATE.

NTHREADS=number-of-threads

specifies the number of threads per computation node. The default value is the lesser of 16 and the number of threads available per computation node.

RANKTHRESHOLD=number

specifies the value of epsilon for determining the rank of the kernel matrix. The default number is 10 Superscript negative 8.

SCALE

scales the observations by the standard deviation of each column. If a constant variable exists (where all observations have the same value), the observations of this column are not scaled.

Last updated: November 11, 2020