Q: Where is the data from?
Data is downloaded from webpage: http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones
Direct link for the data for this project is: https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip
Q: How big is the data sets?
296M
Q: What is the data about?
30 people (variable name: subjectID) taking 6 activities (activities), measured by accelerometer and gyroscope. Each record lists out 561 variables including means, standard deviation, median....of the measured signals (for details , see feature.txt).
Training data set 70% Testing data set 30%
Q: What does the program do to the data?
- Merges the training and the test sets to create one data set.
- Uses descriptive activity names to name the activities in the data set (ex, 'Walking' and 'Walking_Upstairs' instead of 1 and 2)
- Extracts only the measurements on the mean and standard deviation for each measurement. (Only means and standard deviation of measurements are extracted, angle(....mean) is not included)
- Appropriately labels the data set with descriptive variable names. (Make it R leagal, (), -, etc are illegal in variable names)
- From the data set in step 4, creates a second, independent tidy data set with the average of each variable for each activity and each subjectID.
Q: What is the output of the program?
Two data sets are saved, as a result.
- It saves the data set, extracted to contain only measurements on the mean and standard deviation for each measurement. Filename: './extract.txt'
- It saves the data set, extracted to calculate average of each variable in './extract.txt' for each activity and each sujectID. Filename: './mean.txt'