Introduction

This assignment uses data orginally from the UC Irvine Machine Learning Repository for machine learning datasets.

The data linked to from the course website represent data collected from the accelerometers from the Samsung Galaxy S smartphone. A full description of the dataset is available at the site where the data was obtained:

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

The data used for the project were downloaded from the course website here:

https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip [61MB]

This repository contains an R script named run_analysis.R that does the following.

1. Merges the training and the test sets into one data set.

2. Extracts only the measurements on the mean and standard deviation for each measurement from the input dataset.

3. Creates descriptive activity names for the activities in the data set

4. Labels the data set with descriptive variable names.

5. Produces an independent tidy data set (har_activities_summary.txt) with the mean of each variable for each activity and each subject.

• Dataset: [20Mb]

• Description: Measures from an embedded accelerometer and gyroscope, that captured 3-axial linear acceleration and 3-axial angular velocity at a constant rate of 50Hz.

The following descriptions of the 68 variables in the dataset are taken from the description of the data available from the UCI web site:

The column number, variable, the derivation of the variables are show for each variable.

• pid Participant id range is 1:30
• activity Name of the activity
• 1 mean.tBodyAcc.mean...X Mean of tBodyAcc-mean()-X
• 2 mean.tBodyAcc.mean...Y Mean of tBodyAcc-mean()-Y
• 3 mean.tBodyAcc.mean...Z Mean of tBodyAcc-mean()-Z
• 4 mean.tBodyAcc.std...X Mean of tBodyAcc-std()-X
• 5 mean.tBodyAcc.std...Y Mean of tBodyAcc-std()-Y
• 6 mean.tBodyAcc.std...Z Mean of tBodyAcc-std()-Z
• 41 mean.tGravityAcc.mean...X Mean of tGravityAcc-mean()-X
• 42 mean.tGravityAcc.mean...Y Mean of tGravityAcc-mean()-Y
• 43 mean.tGravityAcc.mean...Z Mean of tGravityAcc-mean()-Z
• 44 mean.tGravityAcc.std...X Mean of tGravityAcc-std()-X
• 45 mean.tGravityAcc.std...Y Mean of tGravityAcc-std()-Y
• 46 mean.tGravityAcc.std...Z Mean of tGravityAcc-std()-Z
• 81 mean.tBodyAccJerk.mean...X Mean of tBodyAccJerk-mean()-X
• 82 mean.tBodyAccJerk.mean...Y Mean of tBodyAccJerk-mean()-Y
• 83 mean.tBodyAccJerk.mean...Z Mean of tBodyAccJerk-mean()-Z
• 84 mean.tBodyAccJerk.std...X Mean of tBodyAccJerk-std()-X
• 85 mean.tBodyAccJerk.std...Y Mean of tBodyAccJerk-std()-Y
• 86 mean.tBodyAccJerk.std...Z Mean of tBodyAccJerk-std()-Z
• 121 mean.tBodyGyro.mean...X Mean of tBodyGyro-mean()-X
• 122 mean.tBodyGyro.mean...Y Mean of tBodyGyro-mean()-Y
• 123 mean.tBodyGyro.mean...Z Mean of tBodyGyro-mean()-Z
• 124 mean.tBodyGyro.std...X Mean of tBodyGyro-std()-X
• 125 mean.tBodyGyro.std...Y Mean of tBodyGyro-std()-Y
• 126 mean.tBodyGyro.std...Z Mean of tBodyGyro-std()-Z
• 161 mean.tBodyGyroJerk.mean...X Mean of tBodyGyroJerk-mean()-X
• 162 mean.tBodyGyroJerk.mean...Y Mean of tBodyGyroJerk-mean()-Y
• 163 mean.tBodyGyroJerk.mean...Z Mean of tBodyGyroJerk-mean()-Z
• 164 mean.tBodyGyroJerk.std...X Mean of tBodyGyroJerk-std()-X
• 165 mean.tBodyGyroJerk.std...Y Mean of tBodyGyroJerk-std()-Y
• 166 mean.tBodyGyroJerk.std...Z Mean of tBodyGyroJerk-std()-Z
• 201 mean.tBodyAccMag.mean.. Mean of tBodyAccMag-mean()
• 202 mean.tBodyAccMag.std.. Mean of tBodyAccMag-std()
• 214 mean.tGravityAccMag.mean.. Mean of tGravityAccMag-mean()
• 215 mean.tGravityAccMag.std.. Mean of tGravityAccMag-std()
• 227 mean.tBodyAccJerkMag.mean.. Mean of tBodyAccJerkMag-mean()
• 228 mean.tBodyAccJerkMag.std.. Mean of tBodyAccJerkMag-std()
• 240 mean.tBodyGyroMag.mean.. Mean of tBodyGyroMag-mean()
• 241 mean.tBodyGyroMag.std.. Mean of tBodyGyroMag-std()
• 253 mean.tBodyGyroJerkMag.mean.. Mean of tBodyGyroJerkMag-mean()
• 254 mean.tBodyGyroJerkMag.std.. Mean of tBodyGyroJerkMag-std()
• 266 mean.fBodyAcc.mean...X Mean of fBodyAcc-mean()-X
• 267 mean.fBodyAcc.mean...Y Mean of fBodyAcc-mean()-Y
• 268 mean.fBodyAcc.mean...Z Mean of fBodyAcc-mean()-Z
• 269 mean.fBodyAcc.std...X Mean of fBodyAcc-std()-X
• 270 mean.fBodyAcc.std...Y Mean of fBodyAcc-std()-Y
• 271 mean.fBodyAcc.std...Z Mean of fBodyAcc-std()-Z
• 345 mean.fBodyAccJerk.mean...X Mean of fBodyAccJerk-mean()-X
• 346 mean.fBodyAccJerk.mean...Y Mean of fBodyAccJerk-mean()-Y
• 347 mean.fBodyAccJerk.mean...Z Mean of fBodyAccJerk-mean()-Z
• 348 mean.fBodyAccJerk.std...X Mean of fBodyAccJerk-std()-X
• 349 mean.fBodyAccJerk.std...Y Mean of fBodyAccJerk-std()-Y
• 350 mean.fBodyAccJerk.std...Z Mean of fBodyAccJerk-std()-Z
• 424 mean.fBodyGyro.mean...X Mean of fBodyGyro-mean()-X
• 425 mean.fBodyGyro.mean...Y Mean of fBodyGyro-mean()-Y
• 426 mean.fBodyGyro.mean...Z Mean of fBodyGyro-mean()-Z
• 427 mean.fBodyGyro.std...X Mean of fBodyGyro-std()-X
• 428 mean.fBodyGyro.std...Y Mean of fBodyGyro-std()-Y
• 429 mean.fBodyGyro.std...Z Mean of fBodyGyro-std()-Z
• 503 mean.fBodyAccMag.mean.. Mean of fBodyAccMag-mean()
• 504 mean.fBodyAccMag.std.. Mean of fBodyAccMag-std()
• 516 mean.fBodyBodyAccJerkMag.mean.. Mean of fBodyBodyAccJerkMag-mean()
• 517 mean.fBodyBodyAccJerkMag.std.. Mean of fBodyBodyAccJerkMag-std()
• 529 mean.fBodyBodyGyroMag.mean.. Mean of fBodyBodyGyroMag-mean()
• 530 mean.fBodyBodyGyroMag.std.. Mean of fBodyBodyGyroMag-std()
• 542 mean.fBodyBodyGyroJerkMag.mean.. Mean of fBodyBodyGyroJerkMag-mean()
• 543 mean.fBodyBodyGy+A12:C70roJerkMag.std.. Mean of fBodyBodyGyroJerkMag-std()