plot4.R

# Read and setup data
data0 <- read.csv( 
    "household_power_consumption.txt" , 
    sep=";" , 
    na.strings="?" 
  )

data0$dt <- strptime( 
    paste( data0$Date , data0$Time ) , 
    format="%d/%m/%Y %H:%M:%S" 
  )

data <- data0[ 
    !is.na(data0$dt) 
    & data0$dt > strptime( "2007-01-31 23:59:00" , format="%Y-%m-%d %H:%M:%S" ) 
    & data0$dt < strptime( "2007-02-03" , format="%Y-%m-%d" ) 
  , ]

# Plot
png( filename="plot4.png" )

par( mfrow=c(2,2) )

plot( 
  data$dt ,
  data$Global_active_power ,
  type="l" ,
  xlab="" ,
  ylab="Global Active Power"
)

plot( 
  data$dt ,
  data$Voltage ,
  type="l" ,
  xlab="datetime" ,
  ylab="Voltage"
)

plot(
  data$dt ,
  data$Sub_metering_1 ,
  type="l" ,
  xlab="" ,
  ylab="Energy sub metering"
)
lines(
  data$dt ,
  data$Sub_metering_2 ,
  col="red"
)
lines(
  data$dt ,
  data$Sub_metering_3 ,
  col="blue"
)
legend(
  "topright" ,
  legend=c(
    "Sub_metering_1" ,
    "Sub_metering_2" ,
    "Sub_metering_3"
  ) ,
  col=c(
    "black" ,
    "red" ,
    "blue"
  ) ,
  lty="solid" ,
  bty="n"
)

plot(
  data$dt ,
  data$Global_reactive_power ,
  type="l" ,
  xlab="datetime" ,
  ylab="Global_reactive_power"
)

dev.off()