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plot2.R
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plot2.R
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# 1. Read the data into R
data<-read.table("./exdata_data_household_power_consumption/household_power_consumption.txt",
sep=";",header=TRUE)
str(data)
View(data)
# 2. Convert the Date and Time variables to Date/Time classes
data$Date<-as.Date(data$Date,"%d/%m/%Y")
data$Time<-format(strptime(data$Time, "%H:%M:%S"),"%H:%M:%S")
# 3. Extract the data from '2007-02-01' to '2007-02-02'
data1<-data[which(data$Date %in% c(as.Date('2007-02-01'),as.Date('2007-02-02'))),]
View(data1)
str(data1)
# 4. Convert some variables into numeric
data1$Global_reactive_power<-as.numeric(data1$Global_reactive_power)
data1$Global_active_power<-as.numeric(data1$Global_active_power)
# 5. Construct plots and create PNG files
## Plot2:
# Construct variable of weekdays
data1$weekdays<-weekdays(data1$Date)
# get the location of axis labels
table(data1$weekdays)
# construct plots
with(data1,plot(Global_active_power,type="n",
ylab="Global Active Power (kilowatts)",xlab="",xaxt="n"))
with(data1,lines(Global_active_power))
axis(side=1,at=c(0,1441,2880),labels=c("Thu","Fri","Sat"))
dev.copy(png,file="plot2.png",width = 480, height = 480,units = "px")
dev.off()