plot4.R

#############################################################################
# Exploratory Data Analysis
# John Hopkins University
# Coursera Course Project
# Author: Anand Rao
# Date: 06 Sep 2014
# Project #1
##############################################################################

require(sqldf)


setwd("~/My Courses/ExploratoryDataAnalysis/Projects")


## Read Data for just the dates 1/2/2007 and 2/2/2007
data <- read.csv.sql( file='household_power_consumption.txt',
                      sep=";",
                      sql="select * from file where Date = '1/2/2007' or Date = '2/2/2007'",
                      header=TRUE)

data$datetime <- as.POSIXct(paste(data$Date, data$Time), format = "%d/%m/%Y %T")

## Open PNG device and create a plot "Plot2" in working directory with 
## Width of 480 pixels and height of 480 pixels
png(filename="Plot4.png", width=480, height=480)


par(mfrow=c(2,2))

### Create the first plot

        ## Create a base plot frame with a new Y-axis label and X-axis label
        with(data, plot(datetime, Global_active_power, 
                xlab="", 
                ylab = "Global Active Power", 
                type="n"))
        ## Draw the lines for the graph
        with(data, lines(datetime, Global_active_power))

### Create the second plot

        ## Create a base plot frame with a new Y-axis label and X-axis label
        with(data, plot(datetime, Voltage, 
                ylab = "Voltage", 
                type="n"))
        ## Draw the lines for the graph
        with(data, lines(datetime, Voltage))


### Create the third plot

        ## Create a base plot frame with a new Y-axis label and X-axis label
        with(data, plot(datetime, Sub_metering_1, 
                xlab="", 
                ylab = "Energy sub metering", 
                type="n"))
        ## Draw the line for Sub_metering_1 in Black color
        with(data, lines(datetime, Sub_metering_1, col="black"))
        ## Draw the line for Sub_metering_2 in Red color
        with(data, lines(datetime, Sub_metering_2, col="red"))
        ## Draw the line for Sub_metering_3 in Blue color
        with(data, lines(datetime, Sub_metering_3, col="blue"))
        legend("topright", lty=1, 
                col=c("black", "red", "blue"), 
                bty="n",
               legend = c("Sub_metering_1","Sub_metering_2", "Sub_metering_3"))

### Create the fourth plot

        ## Create a base plot frame with a new Y-axis label and X-axis label
        with(data, plot(datetime, Global_reactive_power, 
                type="n"))
        ## Draw the lines for the graph
        with(data, lines(datetime, Global_reactive_power))




## Close the PNG file device
dev.off()