run_analysis.R

This script contains a function run_analysis() that performs the following actions on the "UCI HAR Dataset":

The test data frame

1. Creates a new data frame called 'test' to hold the focused data from the test set
2. Finds the mean and standard deviation columns the test data and adds it to the test variable
3. Appends the activity numbers from the test data as a new column in the test variable
4. Appends the subject numbers from the test data as a new column in the test variable

The train data frame

1. Creates a new data frame called 'train' to hold the focused data from the train set
2. Finds the mean and standard deviation columns the train data and adds it to the train variable
3. Appends the activity numbers from the train data as a new column in the train variable
4. Appends the subject numbers from the train data as a new column in the train variable

The train and test data frames are then concatinated into a single data table called full

The mean of each column per activity per subject is then used to create a data table called tidy which is returned as the output of the function.

The resulting columns are:

• "subject" - The id of the subject
• "activity" - The activity the subject is performing
• "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"
• "fBodyBodyGyroMag-mean"
• "fBodyBodyGyroMag-std"
• "fBodyBodyGyroJerkMag-mean"
• "fBodyBodyGyroJerkMag-std"