diff --git a/README.md b/README.md index 05bd5e0a6d3..d4c0d752a9e 100644 --- a/README.md +++ b/README.md @@ -1,4 +1,114 @@ -ExData_Plotting1 -================ +## Introduction + +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: + +
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  1. Date: Date in format dd/mm/yyyy
  2. +
  3. Time: time in format hh:mm:ss
  4. +
  5. Global_active_power: household global minute-averaged active power (in kilowatt)
  6. +
  7. Global_reactive_power: household global minute-averaged reactive power (in kilowatt)
  8. +
  9. Voltage: minute-averaged voltage (in volt)
  10. +
  11. Global_intensity: household global minute-averaged current intensity (in ampere)
  12. +
  13. 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).
  14. +
  15. 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.
  16. +
  17. 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.
  18. +
+ +## Loading the data + + + + + +When loading the dataset into R, please consider the following: + +* The dataset has 2,075,259 rows and 9 columns. First +calculate a rough estimate of how much memory the dataset will require +in memory before reading into R. Make sure your computer has enough +memory (most modern computers should be fine). + +* We will only be using data from the dates 2007-02-01 and +2007-02-02. One alternative is to read the data from just those dates +rather than reading in the entire dataset and subsetting to those +dates. + +* You may find it useful to convert the Date and Time variables to +Date/Time classes in R using the `strptime()` and `as.Date()` +functions. + +* Note that in this dataset missing values are coded as `?`. + + +## Making Plots + +Our overall goal here is simply to examine how household energy usage +varies over a 2-day period in February, 2007. Your task is to +reconstruct the following plots below, all of which were constructed +using the base plotting system. + +First you will need to fork and clone the following GitHub repository: +[https://github.com/rdpeng/ExData_Plotting1](https://github.com/rdpeng/ExData_Plotting1) + + +For each plot you should + +* Construct the plot and save it to a PNG file with a width of 480 +pixels and a height of 480 pixels. + +* Name each of the plot files as `plot1.png`, `plot2.png`, etc. + +* Create a separate R code file (`plot1.R`, `plot2.R`, etc.) that +constructs the corresponding plot, i.e. code in `plot1.R` constructs +the `plot1.png` plot. Your code file **should include code for reading +the data** so that the plot can be fully reproduced. You should also +include the code that creates the PNG file. + +* Add the PNG file and R code file to your git repository + +When you are finished with the assignment, push your git repository to +GitHub so that the GitHub version of your repository is up to +date. There should be four PNG files and four R code files. + + +The four plots that you will need to construct are shown below. + + +### Plot 1 + + +![plot of chunk unnamed-chunk-2](figure/unnamed-chunk-2.png) + + +### Plot 2 + +![plot of chunk unnamed-chunk-3](figure/unnamed-chunk-3.png) + + +### Plot 3 + +![plot of chunk unnamed-chunk-4](figure/unnamed-chunk-4.png) + + +### Plot 4 + +![plot of chunk unnamed-chunk-5](figure/unnamed-chunk-5.png) -Plotting Assignment 1 for Exploratory Data Analysis