R/utility.R

In WXCode/AD616: Decision Trees and Stochastic Optimization

#Utility Functions
library(grid)
multiplot <- function(..., plotlist=NULL, file, cols=1, layout=NULL) {
  # Make a list from the ... arguments and plotlist
  plots <- c(list(...), plotlist)

  numPlots = length(plots)

  # If layout is NULL, then use 'cols' to determine layout
  if (is.null(layout)) {
    # Make the panel
    # ncol: Number of columns of plots
    # nrow: Number of rows needed, calculated from # of cols
    layout <- matrix(seq(1, cols * ceiling(numPlots/cols)),
                     ncol = cols, nrow = ceiling(numPlots/cols))
  }

  if (numPlots==1) {
    print(plots[[1]])

  } else {
    # Set up the page
    grid.newpage()
    pushViewport(viewport(layout = grid.layout(nrow(layout), ncol(layout))))

    # Make each plot, in the correct location
    for (i in 1:numPlots) {
      # Get the i,j matrix positions of the regions that contain this subplot
      matchidx <- as.data.frame(which(layout == i, arr.ind = TRUE))

      print(plots[[i]], vp = viewport(layout.pos.row = matchidx$row,
                                      layout.pos.col = matchidx$col))
    }
  }
}


rlnorm2<-function(n,mean,sd){
  rlnorm(n,log(mean*(1+sd^2/mean^2)^-.5),log(1+sd^2/mean^2)^.5)
}

rtri<-function(n,min,ml,max){
  qtri<-function(U){
    F<-(ml-min)/(max-min)
    if (U<F) {min+(U*(max-min)*(ml-min))^.5}
    else {max-((1-U)*(max-min)*(max-ml))^.5}
  }
  y<-runif(n)
  sapply(y,qtri)
}