Plot2.R

# Reading, naming and subsetting power consumption data
power <- read.table("household_power_consumption.txt", skip=1, sep=";")
names(power) <- c("Date", "Time", "Global_active_power", "Global_reactive_power", "Voltage", "Global_intensity", "Sub_metering_1", "Sub_metering_2", "Sub_metering_3")
subpower <- subset(power, power$Date == "1/2/2007" | power$Date == "2/2/2007")

# Transforming the Date and Time vars from characters into objects of type Date and POSIXlt respectively
subpower$Date <- as.Date(subpower$Date, format="%d/%m/%Y")
subpower$Time <- strptime(subpower$Time, format="%H:%M:%S")
subpower[1:1440, "Time"] <- format(subpower[1:1440, "Time"], "2007-02-01 %H:%M:%S")
subpower[1441:2880, "Time"] <- format(subpower[1441:2880, "Time"], "2007-02-02 %H:%M:%S")


# calling the basic plot function
plot(subpower$Time, as.numeric(as.character(subpower$Global_active_power)), type="l", xlab="", ylab="Global Active Power (kilowatts)") 

# annotating graph
title(main="Global Active Power Vs Time")