last plot

Author: pinogl

plot4.R

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+# setwd("E:/Courses/Coursera/DSS4 - EDA/projects/prj1")
+
+# set locale in order to get English names for time related variables
+Sys.setlocale("LC_TIME", "English")
+
+# define the columns dataype
+cols <- c(rep("character", 2), rep("numeric", 7))
+
+# compute skip and nrows parameters for read.table function 
+d0 <- as.POSIXct("16/12/2006 17:24:00", format="%d/%m/%Y %H:%M:%S")
+d1 <- as.POSIXct("1/2/2007", format="%d/%m/%Y")
+d2 <- as.POSIXct("3/2/2007", format="%d/%m/%Y")
+skip <- as.numeric(difftime(d1, d0, units="mins")) + 1 # header row
+nrows <-  as.numeric(difftime(d2, d1, units="mins"))
+
+# read only the required part fo the data set
+hepc <- read.table("household_power_consumption.txt", sep=";", colClasses=cols,
+                   nrows=nrows, skip=skip, stringsAsFactors=FALSE,
+                   na.strings="?", comment.char="")
+
+# set the name from the first row
+names(hepc) <-  read.table("household_power_consumption.txt", sep=";", nrows=1,
+                           stringsAsFactors=FALSE)
+
+# create the datetime variable
+hepc$datetime <- as.POSIXct(paste(hepc$Date, hepc$Time, sep=" "),
+                            format="%d/%m/%Y %H:%M:%S")
+
+# add 'day of week' variable
+hepc$dow = as.factor(weekdays(hepc$datetime, abbreviate=TRUE))  # day of week
+
+# keep only relevantvariables and reorder them
+hepc <- hepc[c(10:11, 3:9)]
+
+# Plot4
+png(file="plot4.png", width=480, height=480, bg="transparent")
+
+par(mfrow=c(2,2))
+
+with(hepc, {
+    plot(datetime, Global_active_power, type = "l", xlab = "", 
+         ylab = "Global Active Power", main = "")
+    
+    plot(datetime, Voltage, type = "l", main = "")
+    
+    plot(hepc$datetime, hepc$Sub_metering_1, type = "n", xlab = "", 
+         ylab = "Energy sub metering", main = "")
+    lines(hepc$datetime, hepc$Sub_metering_1, col = "black")
+    lines(hepc$datetime, hepc$Sub_metering_2, col = "red")
+    lines(hepc$datetime, hepc$Sub_metering_3, col = "blue")
+    legend("topright", names(hepc)[7:9], col=c('black','red', 'blue'), bty="n")
+    
+    plot(datetime, Global_reactive_power, type = "l", main = "")    
+})
+
+dev.off()
+
+# reset time locale to the default value
+Sys.setlocale("LC_TIME", "")