plot2.R

# read data
data_ <- read.table("household_power_consumption.txt", sep = ";", na.strings = "?", header = T);
# Convert date and time
data_$Time <- strptime(x = paste(data_$Date, data_$Time, sep = " "), format = "%d/%m/%Y %H:%M:%S")
data_$Date <- as.Date(data_$Date,format = '%d/%m/%Y')

start_ <- as.Date("2007-02-01")
end_ <- as.Date("2007-02-02")

data2 <- data_[which(data_$Date >= start_ & data_$Date <= end_),]

# draw plot 2
png(file = "plot2.png", width = 480, height = 480, units = "px")

plot(
  x = data2$Time,
  y = data2$Global_active_power,
  type = "l",
  xlab="",
  ylab="Global Active Power (kilowatts)"
)

dev.off()