plot4.R

read <- function()
{
  fn <- "household_power_consumption.txt"
  
  df <- read.csv(fn,
                 as.is = T,
                 dec = '.',
                 sep = ";",
                 na.strings = "?",
                 skip = 66636,
                 nrows = 2880,
                 col.names = c("Date","Time", "Global_AC", "Global_RC", "V", "Global_Int","Sub_1","Sub_2", "Sub_3"),
                 colClasses = c("character", "character", "numeric", "numeric", "numeric", "numeric", "numeric", "numeric", "numeric"))
  
  df$DateTime <- strptime(paste(df$Date, df$Time),"%d/%m/%Y %H:%M:%S")
  
  df
}

createPlot4 <- function()
{
  df <- read()
  
  # needed this to switch to english day names in cyrilic r studio
  Sys.setlocale("LC_TIME", "English")
  
  par(mfrow = c(2,2))
  
  plot(df$DateTime, df$Global_AC, 
       main = "",
       ylab="Global Active Power (kilowatts)",
       xlab="",
       type="l"
  )
  
  plot(df$DateTime, df$V, 
       main = "",
       ylab="Voltage",
       xlab="datetime",
       type="l"
  )
  
  plot(df$DateTime, df$Sub_1,
       main = "",
       ylab="Energy sub metering",
       xlab="",
       type="l"
  )
  
  lines(df$DateTime, df$Sub_2, col="Red")
  
  lines(df$DateTime, df$Sub_3, col="Blue")
 
  legend("topright", lty=1, cex=0.75, 
         c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"), 
         col=c("Black","Red","Blue"))

  plot(df$DateTime, df$Global_RC, 
       main = "",
       ylab="Global_reactive_power",
       xlab="datetime",
       type="l"
  )
  
  dev.copy(png,
           res= 60, # had to use res to get rid of legend truncating. 
           # could be an issue of windows high-dpi display and so on
           file="plot4.png")
  
  dev.off()
}