library(RColorBrewer)
library(ggplot2)
library(reshape2)
library(grid)
library(gridExtra)

# simply function for getting badrate ----------------------
getBadRate <- function(xVar, yVar){
  tapply(yVar, xVar, sum) / tapply(yVar, xVar, length)
}

# ploting all things I'm talking about ---------------------
doVarStab <- function(yVar, xVar, year, name=NA, dir=getwd()){
  yearUniq <- sort(unique(year))
  xVarUniq <- sort(unique(xVar))
  if(length(xVarUniq) > 9) {stop("zbyt wiele do dpzoailu")}
  mBadRate <- matrix(0, nrow = length(xVarUniq), ncol = length(yearUniq))
  w <- 1
  for (i in yearUniq){
    idx <- which(year==i)
    mBadRate[w : (w + length(xVarUniq) - 1)] <- getBadRate(xVar = xVar[idx], yVar = yVar[idx])
    w <- w + length(xVarUniq)
  }


  #line plots for badrate
  mBadRate <- melt(mBadRate)
  colnames(mBadRate) <- c("variable", "year", "badrate")
  mBadRate[, 2] <- as.factor(mBadRate[, 2])

  p1 <- ggplot(mBadRate, aes(variable, badrate, group = year, colour = year)) +
    geom_line(size=1) +
    geom_point(size=3, shape=1) +
    scale_colour_brewer(palette = "Set1") +
    theme_minimal()

  #barplots for structure of variable
  dt <- data.frame(xVar, year)
  p2 <- ggplot(dt, aes(year, fill=xVar)) +
    geom_bar( position="fill") +
    scale_fill_brewer(palette = "Set1") +
    theme_minimal()

  #save graphs

  grid.arrange(p2, p1, ncol = 2, top=name)

}


# example -----------------------------------
dt <- data.frame(def=rep(c(TRUE,FALSE),each=50),
                 b=c(rep(c("a","b"),each=30), rep("c",40)),
                 c=sample(c("xx","yy","zz"),100,replace=T),
                 rok=sample(2012:2015,100,replace=T))
dt
doVarStab(yVar=dt$def, xVar=dt$b, year=dt$rok, name="trololo")