#
#   DTMC.R - A set of R functions for simulating M/M/k queues
#            
#Copyright (C) 2004 Fernando Henrique F. P. Rosa  <feferraz at ime.usp.br>
#                   Vagner Aparecido Pedro Junior <vapjunior at hotmail.com>
#   
# 
#This program is free software; you can redistribute it and/or
#modify it under the terms of version 2 of the GNU General Public License
#as published by the Free Software Foundation.  A copy of this license should
#be included in the file COPYING.
#
#This program is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#GNU General Public License for more details.
#
#You should have received a copy of the GNU General Public License
#along with this program; if not, write to the Free Software
#Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
#
#
# Última data de edição: 20050915
# Descrição: esse conjunto de funções simula diversos processos de fila
# M/M/k. Para descrição da motivação e algum desenvolvimento teórico veja:
# http://www.feferraz.net/files/lista/mae312-trabalho.pdf




estima.Pn <- function(n,sistema,inicial,final) {
        sucessos <- 0
        L <- length(sistema)
        if (n > L) { stop('unable to estimate over more steps than sampled.') }
        tamanho.janela <- n
        N <- L-n
        for (i in 1:N) {
                a <- sistema[i]
                b <- sistema[i+n]
                if (a != inicial) { N <- N -1 }
                else if (b == final) { sucessos <- sucessos + 1 }
        }
        sucessos/N
}

estima.matriz.ineficiente <- function(space,n=1,na.action=na.omit) {
    na.action <- match.fun(na.action)
    space <- na.action(space)
	trans <- matrix(rep(0,length(unique(space))^2),ncol=length(unique(space)))
	colnames(trans) <- sort(unique(space))
	row.names(trans) <- sort(unique(space))
	for (i in seq(along=unique(space))) {
		for (j in seq(along=unique(space))) {
			trans[i,j] <- estima.Pn(n,space,sort(unique(space))[i],sort(unique(space))[j])
		}
	}

	trans
}

simula <- function(trans,N) {
        transita <- function(char,trans) {
                sample(colnames(trans),1,prob=trans[char,])
        }

	sim <- character(N)
	sim[1] <- sample(colnames(trans),1)
	for (i in 2:N) {
		sim[i] <- transita(sim[i-1],trans)
	}

	sim
}

estima.matriz <- function(space,na.action=na.omit) {
    na.action <- match.fun(na.action)
    space <- na.action(space)
	trans <- matrix(.C("estima_matriz",as.integer(factor(space)),as.integer(length(space)),as.integer(length(unique(space))),trans=double(length(unique(space))^2),DUP=FALSE)$trans,ncol=length(unique(space)),byrow=T)
	colnames(trans) <- sort(unique(space))
	row.names(trans) <- sort(unique(space))
	trans
}

le.espaco <- function(file) {
	scan(file,what=character(),n=-1,sep="\n")
}

cat.simulairc <- function(v,file="") {
 v <- gsub("^N(.*)N$","<\\1>",v)
 v <- gsub("CR","\n",v)
 v <- paste(v,collapse=' ')
 cat(v,file=file)
}

cat.simulatxt <- function(v,file="") {
 v <- gsub("CR","\n",v)
 v <- paste(v,collapse=' ')
 cat(v,file=file)
}