plot1.R

# download the file if necessary
if (!file.exists("household_power_consumption.txt")) {
  if (!file.exists("exdata-data-household_power_consumption.zip")) {
    download.file("https://d396qusza40orc.cloudfront.net/exdata%2Fdata%2Fhousehold_power_consumption.zip", destfile="exdata-data-household_power_consumption.zip", method="curl")
  }
  unzip("exdata-data-household_power_consumption.zip")
}

# load data
data <- read.table("household_power_consumption.txt", header=TRUE, sep=";", na.strings="?", colClasses=c("character", "character", "numeric", "numeric", "numeric", "numeric", "numeric", "numeric", "numeric"))

# extract selected dates
data <- rbind(data[data$Date=="1/2/2007",], data[data$Date=="2/2/2007",])



# figure 1 - Global_active_power
png(filename="plot1.png")
hist(data$Global_active_power, main="Global Active Power", xlab="Global Active Power (kilowatts)", ylab="Frequency", col="red")
dev.off()