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# S4 class for NMG algorithms
#
# Author: Renaud Gaujoux
###############################################################################
#' @include algorithmic.R
#' @include NMFSet-class.R
NULL
#' Generic Strategy Class
#'
#' This class defines a common interface for generic algorithm strategies
#' (e.g., \code{\linkS4class{NMFStrategy}}).
#'
#' @slot name character string giving the name of the algorithm
#' @slot package name of the package that defined the strategy.
#' @slot defaults default values for some of the algorithm's arguments.
#'
#' @keywords internal
setClass('Strategy'
, contains = 'VIRTUAL'
, representation = representation(
name = 'character' # the strategy name
, package = 'character' # the package that defines the strategy
, defaults = 'list'
)
, prototype = prototype(
package = character()
, name = character()
)
, validity=function(object){
# slot 'name' must be a non-empty character string
obj <- name(object)
if( !length(obj) || (length(obj)>1L || obj=='') )
return(str_c("Slot 'name' must be a single non-empty character string [", obj, ']'))
TRUE
}
)
#' Accessing Strategy Names
#'
#' \code{name} and \code{name<-} gets and sets the name associated with an object.
#' In the case of \code{Strategy} objects it is the the name of the algorithm.
#'
#' @param object an R object with a defined \code{name} method
#' @param ... extra arguments to allow extension
#' @param value replacement value
#'
#' @export
#' @inline
#' @rdname Strategy-class
setGeneric('name', function(object, ...) standardGeneric('name'))
#' Returns the name of an algorithm
#' @param all a logical that indicates if all the names associated with a strategy
#' should be returned (\code{TRUE}), or only the first (primary) one (\code{FALSE}).
setMethod('name', signature(object='Strategy'),
function(object, all=FALSE){
n <- slot(object, 'name')
if( length(n) && !all ) n[1L] else n
}
)
#' @export
#' @inline
#' @rdname Strategy-class
setGeneric('name<-', function(object, ..., value) standardGeneric('name<-'))
#' Sets the name(s) of an NMF algorithm
setReplaceMethod('name', signature(object='Strategy', value='character'),
function(object, value){
slot(object, 'name') <- value
validObject(object)
object
}
)
defaultArgument <- function(name, object, value, force=FALSE){
# taken from methods::hasArg
aname <- as.character(substitute(name))
miss <- eval(substitute(missing(name)), sys.frame(sys.parent()))
defaults <- attr(object, 'defaults')
if( !miss && !force ) eval(substitute(name), sys.frame(sys.parent()))
else if( aname %in% names(defaults) ) defaults[[aname]]
else value
}
#' Virtual Interface for NMF Algorithms
#'
#' This class partially implements the generic interface defined for general
#' algorithms defined in the \pkg{NMF} package (see \code{\link{algorithmic-NMF}}).
#'
#' @slot objective the objective function associated with the algorithm (Frobenius, Kullback-Leibler, etc...).
#' It is either an access key of a registered objective function or a function definition.
#' In the latter case, the given function must have the following signature \code{(x="NMF", y="matrix")}
#' and return a nonnegative real value.
#'
#' @slot model a character string giving either the (sub)class name of the NMF-class instance used
#' and returned by the strategy, or a function name.
#'
#' @slot mixed a logical that indicates if the algorithm works on mixed-sign data.
#'
#' @keywords internal
setClass('NMFStrategy'
, representation(
objective = '.functionSlot' # the objective function used to compute the error (defined by name or function)
, model = 'character' # NMF model to use
, mixed = 'logical' # can the input data be negative?
)
, prototype=prototype(objective='euclidean', model='NMFstd', mixed=FALSE)
, validity=function(object){
# slot 'objective' must either be a non-empty character string or a function
obj <- objective(object)
if( is.character(obj) && obj == '' )
return("Slot 'objective' must either be a non-empty character string or a function definition.")
# slot 'model' must be the name of a class that extends class 'NMF'
obj <- modelname(object)
if( !is.character(obj) )
return("Slot 'model' must be a character vector")
if( any(inv <- !sapply(obj, isNMFclass)) )
return(paste("Slot 'model' must contain only names of a class that extends class 'NMF' [failure on class(es) "
, paste( paste("'", obj[inv], "'", sep=''), collapse=', ')
,"]"
, sep=''))
# slot 'mixed' must be a single logical
obj <- slot(object, 'mixed')
if( length(obj) != 1 )
return( paste("Slot 'mixed' must be a single logical [length=", length(obj), "]", sep='') )
}
, contains = c('VIRTUAL', 'Strategy')
)
#' @export
#' @rdname NMFStrategy-class
setMethod('show', 'NMFStrategy',
function(object){
cat('<object of class: ', class(object), ">\n", sep='')
cat(" name: ", name(object), " [", packageSlot(object), "]\n", sep='')
svalue <- objective(object)
svalue <- if( is.function(svalue) ) str_args(svalue, exdent=10) else paste("'", svalue,"'", sep='')
cat(" objective:", svalue, "\n")
cat(" model:", modelname(object), "\n")
if( length(object@defaults) > 0L ){
cat(" defaults:", str_desc(object@defaults, exdent=10L), "\n")
}
return(invisible())
}
)
# Coerce method for 'NMFStrategy' objects into 'character': give the main name
setAs('NMFStrategy', 'character'
, def = function(from) name(from)
)
#' Factory Method for NMFStrategy Objects
#'
#' Creates NMFStrategy objects that wraps implementation of NMF algorithms into
#' a unified interface.
#'
#' @param name name/key of an NMF algorithm.
#' @param method definition of the algorithm
#' @param ... extra arguments passed to \code{\link{new}}.
#'
#' @export
#' @inline
setGeneric('NMFStrategy', function(name, method, ...) standardGeneric('NMFStrategy') )
#' Creates an \code{NMFStrategyFunction} object that wraps the function \code{method}
#' into a unified interface.
#'
#' \code{method} must be a function with signature \code{(y="matrix", x="NMFfit", ...)},
#' and return an object of class \code{\linkS4class{NMFfit}}.
setMethod('NMFStrategy', signature(name='character', method='function'),
function(name, method, ...){
# build a NMFStrategyFunction object on the fly to wrap function 'method'
NMFStrategy(name=name, algorithm=method, ...)
}
)
#' Creates an \code{NMFStrategy} object based on a template object (Constructor-Copy).
setMethod('NMFStrategy', signature(name='character', method='NMFStrategy'),
function(name, method, ...){
package <- topns_name()
# build an NMFStrategy object based on template object
strategy <- new(class(method), method, name=name, ..., package=package)
# valid the new strategy
validObject(strategy)
# add trace of inheritance from parent NMF algorithm
attr(strategy, 'parent') <- name(method)[1]
# return new object
strategy
}
)
#' Creates an \code{NMFStrategy} based on a template object (Constructor-Copy),
#' in particular it uses the \strong{same} name.
setMethod('NMFStrategy', signature(name='NMFStrategy', method='missing'),
function(name, method, ...){
# do not change the object if single argument
if( nargs() == 1L ) return(name)
# use the name as a key
# NB: need special trick to avoid conflict between argument and function
mname <- match.fun('name')(name)
NMFStrategy(name=mname, method=name, ...)
}
)
#' Creates an \code{NMFStrategy} based on a registered NMF algorithm that is used
#' as a template (Constructor-Copy), in particular it uses the \strong{same} name.
#'
#' It is a shortcut for \code{NMFStrategy(nmfAlgorithm(method, exact=TRUE), ...)}.
setMethod('NMFStrategy', signature(name='missing', method='character'),
function(name, method, ...){
NMFStrategy(nmfAlgorithm(method, exact=TRUE), ...)
}
)
#' Creates an \code{NMFStrategy} based on a template object (Constructor-Copy)
#' but using a randomly generated name.
setMethod('NMFStrategy', signature(name='NULL', method='NMFStrategy'),
function(name, method, ...){
# use the name as a key
# NB: need special trick to avoid conflict between argument and function
mname <- match.fun('name')(method)
mname <- basename(tempfile(str_c(mname, '_')))
NMFStrategy(name=mname, method=method, ...)
}
)
#' Creates an \code{NMFStrategy} based on a registered NMF algorithm that is used
#' as a template.
setMethod('NMFStrategy', signature(name='character', method='character'),
function(name, method, ...){
NMFStrategy(name=name, method=nmfAlgorithm(method, exact=TRUE), ...)
}
)
#' Creates an \code{NMFStrategy} based on a registered NMF algorithm (Constructor-Copy)
#' using a randomly generated name.
#'
#' It is a shortcut for \code{NMFStrategy(NULL, nmfAlgorithm(method), ...)}.
setMethod('NMFStrategy', signature(name='NULL', method='character'),
function(name, method, ...){
NMFStrategy(NULL, method=nmfAlgorithm(method, exact=TRUE), ...)
}
)
#' Creates an NMFStrategy, determining its type from the extra arguments passed
#' in \code{...}: if there is an argument named \code{Update} then an
#' \code{NMFStrategyIterative} is created, or if there is an argument
#' named \code{algorithm} then an \code{NMFStrategyFunction} is created.
#' Calls other than these generates an error.
#'
setMethod('NMFStrategy', signature(name='character', method='missing'),
function(name, method, ...){
package <- topns_name()
# check iterative strategy
if( hasArg2('Update') ){ # create a new NMFStrategyIterative object
new('NMFStrategyIterative', name=name, ..., package=package)
}else if( hasArg2('algorithm') ){
new('NMFStrategyFunction', name=name, ..., package=package)
}else{
stop('NMFStrategy - Could not infer the type of NMF strategy to instantiate.')
}
}
)
#' Pure virtual method defined for all NMF algorithms to ensure
#' that a method \code{run} is defined by sub-classes of \code{NMFStrategy}.
#'
#' It throws an error if called directly.
#' @rdname NMFStrategy
setMethod('run', signature(object='NMFStrategy', y='matrix', x='NMFfit'),
function(object, y, x, ...){
stop("NMFStrategy::run is a pure virtual method that should be overloaded in class '", class(object),"'.")
}
)
#' Method to run an NMF algorithm directly starting from a given NMF model.
#' @rdname NMFStrategy
setMethod('run', signature(object='NMFStrategy', y='matrix', x='NMF'),
function(object, y, x, ...){
run(object, y, NMFfit(fit=x, seed='none', method=name(object)), ...)
}
)
#' Computes the value of the objective function between the estimate \code{x}
#' and the target \code{y}.
#'
#' @param x an NMF model that estimates \code{y}.
#'
#' @inline
setMethod('deviance', 'NMFStrategy',
function(object, x, y, ...){
obj.fun <- slot(object, 'objective')
# return the distance computed using the strategy's objective function
if( !is.function(obj.fun) )
deviance(x, y, method=obj.fun, ...)
else # directly compute the objective function
obj.fun(x, y, ...)
}
)
#' Gets the objective function associated with an NMF algorithm.
#'
#' It is used in \code{\link[=deviance,NMFStrategy-method]{deviance}}
#' to compute the objective value for an NMF model with respect to
#' a given target matrix.
#'
#' @export
#' @rdname NMFStrategy-class
setMethod('objective', 'NMFStrategy',
function(object){
slot(object, 'objective')
}
)
#' Sets the objective function associated with an NMF algorithm, with a character string
#' that must be a registered objective function.
#' @export
#' @rdname NMFStrategy-class
setReplaceMethod('objective', signature(object='NMFStrategy', value='character'),
function(object, value){
#TODO: test for the existence of objective method
slot(object, 'objective') <- value
validObject(object)
object
}
)
#' Sets the objective function associated with an NMF algorithm, with a function
#' that computes the approximation error between an NMF model and a target matrix.
#' @export
#' @rdname NMFStrategy-class
setReplaceMethod('objective', signature(object='NMFStrategy', value='function'),
function(object, value){
slot(object, 'objective') <- value
validObject(object)
object
}
)
#' Returns the model(s) that an NMF algorithm can fit.
#'
#' @examples
#' # get the type of model(s) associated with an NMF algorithm
#' modelname( nmfAlgorithm('brunet') )
#' modelname( nmfAlgorithm('nsNMF') )
#' modelname( nmfAlgorithm('offset') )
#'
setMethod('modelname', signature(object='NMFStrategy'),
function(object){
slot(object, 'model')
}
)
#' \code{is.mixed} tells if an NMF algorithm works on mixed-sign data.
#' @export
#' @rdname NMFStrategy-class
is.mixed <- function(object){
return( slot(object, 'mixed') )
}
#' Showing Arguments of NMF Algorithms
#'
#' This function returns the extra arguments that can be passed
#' to a given NMF algorithm in call to \code{\link{nmf}}.
#'
#' @param x algorithm specification
#' @param ... extra argument to allow extension
#'
#' @export
nmfFormals <- function(x, ...){
UseMethod('nmfFormals')
}
#' @export
nmfFormals.character <- function(x, ...){
s <- nmfAlgorithm(x)
nmfFormals(s, ...)
}
#' @export
nmfFormals.NMFStrategy <- function(x, ...){
m <- getMethod('run', signature(object='NMFStrategy', y='matrix', x='NMFfit'))
args <- allFormals(m)
# prepend registered default arguments
expand_list(x@defaults, args)
}
#' \code{nmfArgs} is a shortcut for \code{args(nmfWrapper(x))}, to
#' display the arguments of a given NMF algorithm.
#'
#' @rdname nmfFormals
#' @export
#' @examples
#'
#' # show arguments of an NMF algorithm
#' nmfArgs('brunet')
#' nmfArgs('snmf/r')
nmfArgs <- function(x){
args(nmfWrapper(x))
}
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