Code Book for Course Project: Getting and Cleaning Data
Data Source: https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip
The data from the original data source was transformed with run_analysis.R as follows:
-
Merges the training and the test sets (i.e., train/X_train.txt and test/X_test.txt) to create one data set.
-
Extracts only the measurements on the mean and standard deviation for each measurement.
-
Uses descriptive activity names to name the activities in the data set
-
Appropriately labels the data set with descriptive variable names. all feature names (attributes) and activity names are converted to lower case, underscores and brackets () are removed. Then it merges the 10299x66 data frame containing features with 10299x1 data frames containing activity labels and subject IDs. The result is saved as merged_clean_data.txt, a 10299x68 data frame such that the first column contains subject IDs, the second column activity names, and the last 66 columns are measurements. Subject IDs are integers between 1 and 30 inclusive. The data set has the following variables: "subject" "activity" "tbodyacc-mean-x" "tbodyacc-mean-y" "tbodyacc-mean-z" "tbodyacc-std-x" "tbodyacc-std-y" "tbodyacc-std-z" "tgravityacc-mean-x" "tgravityacc-mean-y" "tgravityacc-mean-z" "tgravityacc-std-x" "tgravityacc-std-y" "tgravityacc-std-z" "tbodyaccjerk-mean-x" "tbodyaccjerk-mean-y" "tbodyaccjerk-mean-z" "tbodyaccjerk-std-x" "tbodyaccjerk-std-y" "tbodyaccjerk-std-z" "tbodygyro-mean-x" "tbodygyro-mean-y" "tbodygyro-mean-z" "tbodygyro-std-x" "tbodygyro-std-y" "tbodygyro-std-z" "tbodygyrojerk-mean-x" "tbodygyrojerk-mean-y" "tbodygyrojerk-mean-z" "tbodygyrojerk-std-x" "tbodygyrojerk-std-y" "tbodygyrojerk-std-z" "tbodyaccmag-mean" "tbodyaccmag-std" "tgravityaccmag-mean" "tgravityaccmag-std" "tbodyaccjerkmag-mean" "tbodyaccjerkmag-std" "tbodygyromag-mean" "tbodygyromag-std" "tbodygyrojerkmag-mean" "tbodygyrojerkmag-std" "fbodyacc-mean-x" "fbodyacc-mean-y" "fbodyacc-mean-z" "fbodyacc-std-x" "fbodyacc-std-y" "fbodyacc-std-z" "fbodyaccjerk-mean-x" "fbodyaccjerk-mean-y" "fbodyaccjerk-mean-z" "fbodyaccjerk-std-x" "fbodyaccjerk-std-y" "fbodyaccjerk-std-z" "fbodygyro-mean-x" "fbodygyro-mean-y" "fbodygyro-mean-z" "fbodygyro-std-x" "fbodygyro-std-y" "fbodygyro-std-z" "fbodyaccmag-mean" "fbodyaccmag-std" "fbodybodyaccjerkmag-mean" "fbodybodyaccjerkmag-std" "fbodybodygyromag-mean" "fbodybodygyromag-std" "fbodybodygyrojerkmag-mean" "fbodybodygyrojerkmag-std"
-
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 subject. The result is saved as tidy_data_set_with_the_averages.txt.