plot1.R

#the text file "household_power_consumption.txt" should 
#be downloaded and installed in the working directory 
#before running

png(filename = "plot1.png")

lines <- readLines("household_power_consumption.txt")
rows <- substr(lines, 0, 8) == "1/2/2007" | substr(lines, 0, 8) == "2/2/2007"
rows[1] = TRUE
data <- lines[rows]


t <- read.csv(
	text = data, 
	na.strings = c("?"), 
	sep=";", 
	stringsAsFactors = FALSE)

t$DateTime <- strptime(paste(t$Date, t$Time), "%d/%m/%Y %H:%M:%S")

hist(
	t$Global_active_power, 
	main="Global Active Power", 
	xlab="Global Active Power (kilowatts)", 
	ylab="Frequency", 
	col="red")

dev.off()