This assignment uses data from the UC Irvine Machine Learning Repository, a popular repository for machine learning datasets. In particular, we will be using the "Individual household electric power consumption Data Set" which I have made available on the course web site:

• Dataset: Electric power consumption [20Mb]

• Description: Measurements of electric power consumption in one household with a one-minute sampling rate over a period of almost 4 years. Different electrical quantities and some sub-metering values are available.

The following descriptions of the 9 variables in the dataset are taken from the UCI web site:

1. Date: Date in format dd/mm/yyyy
2. Time: time in format hh:mm:ss
3. Global_active_power: household global minute-averaged active power (in kilowatt)
4. Global_reactive_power: household global minute-averaged reactive power (in kilowatt)
5. Voltage: minute-averaged voltage (in volt)
6. Global_intensity: household global minute-averaged current intensity (in ampere)
7. Sub_metering_1: energy sub-metering No. 1 (in watt-hour of active energy). It corresponds to the kitchen, containing mainly a dishwasher, an oven and a microwave (hot plates are not electric but gas powered).
8. Sub_metering_2: energy sub-metering No. 2 (in watt-hour of active energy). It corresponds to the laundry room, containing a washing-machine, a tumble-drier, a refrigerator and a light.
9. Sub_metering_3: energy sub-metering No. 3 (in watt-hour of active energy). It corresponds to an electric water-heater and an air-conditioner.

The purpose of this project is to load the above data into R and produce four (4) exploratory graphs. This is a guide on how to produce plots 1 to 4, as requested by course project.

• The text file household_power_consumption.txt (semicolon ";" delimited)

• There four R scripts included, each one producing a png file including plots. Each R script consists of two parts:
  • Loading the data into R and transforming it as appropriate:
    • The text file household_power_consumption.txt is read into a data frame
    • Only selected dates are filtered out
    • Date and Time strings are converted to date/time R Types
  • Plotting output
    • Plot1: A Histogram is plotted based on filtered Household power consumption data. Color, Main title, X-axis label and Y-axis limits are specifically set.
    • Plot2: A Plot of type line is plotted based on filtered Household power consumption data. Main title, X-axis and Y-axis labels are specifically set.
    • Plot3: A Plot of type line is plotted based on filtered Household power consumption data. X-axis and Y-axis labels are specifically set. Two extra lines of different colors are plotted on top of it.
    • Plot4: A grid of four plots (2x2) is created. Each plot is added to grid sequentially. The first and second plots are line plot with specific labels, the third plot is a line plot with two extra lines with different colors on top and the third plot is also a line plot with specific labels.

• Four png files (one per R script), plot1.png, ..., plot4.png