This assignment #1 submission for Coursera.org course 'Exploratory Data Analysis' uses data from the UC Irvine Machine Learning Repository, a popular repository for machine learning datasets. In particular, the "Individual household electric power consumption Data Set" is used
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Dataset: Electric power consumption [20Mb]
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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:
- Date: Date in format dd/mm/yyyy
- Time: time in format hh:mm:ss
- Global_active_power: household global minute-averaged active power (in kilowatt)
- Global_reactive_power: household global minute-averaged reactive power (in kilowatt)
- Voltage: minute-averaged voltage (in volt)
- Global_intensity: household global minute-averaged current intensity (in ampere)
- 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).
- 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.
- 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 data transformation applied on all the four R scripts are almost identical and listed out here:
- Reading the Household power consumption dataset file from the zipped file with Headers
- Renaming variable names to improve readability of code
- Create a subset data.frame retaining observations only for two dates i.e. 2007-02-01 and 2007-02-02
- Created a new variable to hold the timestamp (date and time) together for the plots
- Opening the graphic device
- Generating the plot(s) and appending graphics to it as required with appropriate parameters
- Closing the graphic device