klaR: svmlight – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

svmlight

Interface to SVMlight

Description

Function to call SVMlight from R for classification. Multiple group classification is done with the one-against-rest partition of data.

Usage

svmlight(x, ...)

## Default S3 method:
svmlight(x, grouping, temp.dir = NULL, pathsvm = NULL, 
    del = TRUE, type = "C", class.type = "oaa", svm.options = NULL, 
    prior = NULL, out = FALSE, ...)
## S3 method for class 'data.frame'
svmlight(x, ...)
## S3 method for class 'matrix'
svmlight(x, grouping, ..., subset, na.action = na.fail)
## S3 method for class 'formula'
svmlight(formula, data = NULL, ..., subset, 
    na.action = na.fail)

Arguments

`x`	matrix or data frame containing the explanatory variables (required, if `formula` is not given).
`grouping`	factor specifying the class for each observation (required, if `formula` is not given).
`formula`	formula of the form `groups ~ x1 + x2 + ...`. That is, the response is the grouping factor and the right hand side specifies the (non-factor) discriminators.
`data`	Data frame from which variables specified in `formula` are preferentially to be taken.
`temp.dir`	directory for temporary files.
`pathsvm`	Path to SVMlight binaries (required, if path is unknown by the OS).
`del`	Logical: whether to delete temporary files
`type`	Perform `"C"`=Classification or `"R"`=Regression
`class.type`	Multiclass scheme to use. See details.
`svm.options`	Optional parameters to SVMlight. For further details see: “How to use” on http://svmlight.joachims.org/.
`prior`	A Priori probabilities of classes.
`out`	Logical: whether SVMlight output ahouild be printed on console (only for Windows OS.)
`subset`	An index vector specifying the cases to be used in the training sample. (Note: If given, this argument must be named.)
`na.action`	specify the action to be taken if `NA`s are found. The default action is for the procedure to fail. An alternative is `na.omit`, which leads to rejection of cases with missing values on any required variable. (Note: If given, this argument must be named.)
`...`	currently unused

Details

Function to call SVMlight from R for classification (type="C"). SVMlight is an implementation of Vapnik's Support Vector Machine. It is written in C by Thorsten Joachims. On the homepage (see below) the source-code and several binaries for SVMlight are available. If more then two classes are given the SVM is learned by the one-against-all scheme (class.type="oaa"). That means that each class is trained against the other K-1 classes. The class with the highest decision function in the SVM wins. So K SVMs have to be learned. If class.type="oao" each class is tested against every other and the final class is elected by a majority vote.

If type="R" a SVM Regression is performed.

Value

A list containing the function call and the result of SVMlight.

Requirements

SVMlight (http://svmlight.joachims.org/) must be installed before using this interface.

Author(s)

Karsten Luebke, karsten.luebke@fom.de, Andrea Preusser

References

http://svmlight.joachims.org/

Examples

## Not run: 
## Only works if the svmlight binaries are in the path.
data(iris)
x <- svmlight(Species ~ ., data = iris)
## Using RBF-Kernel with gamma=0.1:
data(B3)
x <- svmlight(PHASEN ~ ., data = B3, svm.options = "-t 2 -g 0.1")

## End(Not run)

klaR

Classification and Visualization

v0.6-15

GPL-2 | GPL-3

Authors

Christian Roever, Nils Raabe, Karsten Luebke, Uwe Ligges, Gero Szepannek, Marc Zentgraf, David Meyer

Initial release

2020-02-18