plot2.R

elec<-read.table("exdata-data-household_power_consumption\\household_power_consumption.txt", sep=";", skip=1,  
                 col.names=c("date", "time", "active_power", "inactive_power", "voltage", 
                             "intensity", "meter1", "meter2", "meter3"), 
                 colClasses=c("character", "character", "character","character", "character", 
                              "character","character", "character", "character"));

sub1<-subset(elec, date=="1/2/2007");
sub2<-subset(elec, date=="2/2/2007");

sub<-rbind(sub1, sub2);


# plot 2
active_power<-as.numeric(sub$active_power);
png("plot2.png",width = 480, height = 480)
plot(active_power, type="l", xaxt="n", xlab="datetime", ylab="Global Active Power (kilowatts)");
axis(1, at=c(1,length(sub$date)/2,length(sub$date)), labels=c("Thu","Fri", "Sat"));
dev.off();