plot2.R

#load data.table library
library("data.table")

# Read file
householdEPC <- data.table::fread(input = "../data/household_power_consumption.txt", na.strings="?")

# Convert values to numeric
householdEPC[, Global_active_power := lapply(.SD, as.numeric), .SDcols = c("Global_active_power")]

#Convert to POSIXct to use week days
householdEPC[, dateTime := as.POSIXct(paste(Date, Time), format = "%d/%m/%Y %H:%M:%S")]

# Subset observations from 2007-02-01 to 2007-02-02
householdEPC <- householdEPC[(dateTime >= "2007-02-01") & (dateTime < "2007-02-03")]

png("plot2.png", width=480, height=480)

## Plot 2
plot(x = householdEPC[, dateTime]
     , y = householdEPC[, Global_active_power]
     , type="l", xlab="", ylab="Global Active Power (kilowatts)")

dev.off()