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diff --git a/man/gensvm-package.Rd b/man/gensvm-package.Rd new file mode 100644 index 0000000..56e28ac --- /dev/null +++ b/man/gensvm-package.Rd @@ -0,0 +1,111 @@ +% Generated by roxygen2: do not edit by hand +% Please edit documentation in R/gensvm-package.R +\docType{package} +\name{gensvm-package} +\alias{gensvm-package} +\alias{gensvm.package} +\title{GenSVM: A Generalized Multiclass Support Vector Machine} +\description{ +The GenSVM classifier is a generalized multiclass support vector machine +(SVM). This classifier aims to find decision boundaries that separate the +classes with as wide a margin as possible. In GenSVM, the loss functions +that measures how misclassifications are counted is very flexible. This +allows the user to tune the classifier to the dataset at hand and +potentially obtain higher classification accuracy. Moreover, this +flexibility means that GenSVM has a number of alternative multiclass SVMs as +special cases. One of the other advantages of GenSVM is that it is trained +in the primal space, allowing the use of warm starts during optimization. +This means that for common tasks such as cross validation or repeated model +fitting, GenSVM can be trained very quickly. +} +\details{ +This package provides functions for training the GenSVM model either as a +separate model or through a cross-validated parameter grid search. In both +cases the GenSVM C library is used for speed. Auxiliary functions for +evaluating and using the model are also provided. +} +\section{GenSVM functions}{ + +The main GenSVM functions are: +\describe{ +\item{\code{\link{gensvm}}}{Fit a GenSVM model for specific model +parameters.} +\item{\code{\link{gensvm.grid}}}{Run a cross-validated grid search for +GenSVM.} +} + +For the GenSVM and GenSVMGrid models the following two functions are +available. When applied to a GenSVMGrid object, the function is applied to +the best GenSVM model. +\describe{ +\item{\code{\link{plot}}}{Plot the low-dimensional \emph{simplex} space +where the decision boundaries are fixed (for problems with 3 classes).} +\item{\code{\link{predict}}}{Predict the class labels of new data using the +GenSVM model.} +} + +Moreover, for the GenSVM and GenSVMGrid models a \code{coef} function is +defined: +\describe{ +\item{\code{\link{coef.gensvm}}}{Get the coefficients of the fitted GenSVM +model.} +\item{\code{\link{coef.gensvm.grid}}}{Get the parameter grid of the GenSVM +grid search.} +} + +The following utility functions are also included: +\describe{ +\item{\code{\link{gensvm.accuracy}}}{Compute the accuracy score between true +and predicted class labels} +\item{\code{\link{gensvm.maxabs.scale}}}{Scale each column of the dataset by +its maximum absolute value, preserving sparsity and mapping the data to [-1, +1]} +\item{\code{\link{gensvm.train.test.split}}}{Split a dataset into a training +and testing sample} +\item{\code{\link{gensvm.refit}}}{Refit a fitted GenSVM model with slightly +different parameters or on a different dataset} +} +} + +\section{Kernels in GenSVM}{ + + +GenSVM can be used for both linear and nonlinear multiclass support vector +machine classification. In general, linear classification will be faster but +depending on the dataset higher classification performance can be achieved +using a nonlinear kernel. + +The following nonlinear kernels are implemented in the GenSVM package: +\describe{ + \item{RBF}{The Radial Basis Function kernel is a well-known kernel function + based on the Euclidean distance between objects. It is defined as + \deqn{ + k(x_i, x_j) = exp( -\gamma || x_i - x_j ||^2 ) + } + } + \item{Polynomial}{A polynomial kernel can also be used in GenSVM. This + kernel function is implemented very generally and therefore takes three + parameters (\code{coef}, \code{gamma}, and \code{degree}). It is defined + as: + \deqn{ + k(x_i, x_j) = ( \gamma x_i' x_j + coef)^{degree} + } + } + \item{Sigmoid}{The sigmoid kernel is the final kernel implemented in + GenSVM. This kernel has two parameters and is implemented as follows: + \deqn{ + k(x_i, x_j) = \tanh( \gamma x_i' x_j + coef) + } + } + } +} +\author{ +Gerrit J.J. van den Burg, Patrick J.F. Groenen \cr +Maintainer: Gerrit J.J. van den Burg <gertjanvandenburg@gmail.com> +} +\references{ +Van den Burg, G.J.J. and Groenen, P.J.F. (2016). \emph{GenSVM: A Generalized +Multiclass Support Vector Machine}, Journal of Machine Learning Research, +17(225):1--42. URL \url{http://jmlr.org/papers/v17/14-526.html}. +} + |
