As the project description said, one of the most exciting areas in all of data science right now is wearable computing. The run_analysis.R script submitted for this project reads data collected from the accelerometers from the Samsung Galaxy S smartphone and outputs a summary file that provides the mean of each measurement grouped by Subject and Activity.

Ddata for the project was obtained from:

https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip

Information about the source project is available at the site where the data was obtained:

http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones

What the script does

As requestd in the project, the run_analysis.R reads in various files from the original data set and perform various operations in order to produce the desired summary table. The script depends on the plyr and dplyr libaries. The steps are:

• download the zip file from its source location
• unzip the archive
• load the various files in memory
• merge the training and test sets into a main table
• discard columns that carry measurements that are not means or standard deviations
• add Subject information to the main table
• add Activity information to the main table
• grouping data by Subject and Activity, generate a summary table that provides the mean of each measurement.
• write summary table to file "subject-activity-means.txt"

Running the script from the R command line:

• cd to the root of this project directory
• from R, simply type source ('./run-analysis.R')

Running the script from RStudio:

• Start RStudio
• Set the working directory to the root of this project directory
• type source ('./run-analysis.R') in the console

Reading the summary table into R

To read the summary table generated by this project into R, issue the following command from the R console:

read.table('./subject-activity-means.txt', header=TRUE, sep=" ")