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This codebook is in fulfillment of the course project for the Coursera course entitled "Getting and Cleaning Data" using the UCI HAR Samsung Galaxy S accelerometer and gyroscope dataset [1].
This file contains the list of variables names and their descriptions for the tidy data output of the run_analysis.R script. The output of this script contains the averaged mean and standard deviation measurements for each participant for each activity.
Investigators Reyes-Ortiz et al. recruited 30 participants between the ages of 19 and 48 years and had each perform six activities while wearing a Samsung Galaxy S II smartphone [1]. The purpose of having participants engage in these different physical activities was to assess the signals of gyroscope and accelerometer built into the Samsung Galaxy S II.
Originally, the results of 30-participant dataset were split post-hoc into two groups (training and test). Since these groupings were arbitrary and did not differ in methodology, they were re-grouped for the purposes of the current data cleaning project.
Further details on the original data collection can be found in this project's readme or in the documentation for the UCI HAR dataset [1].
The units of the gyroscope signals are radians/second, and the units of the accelerometer signals are in gravity units (g). Calculated mean frequencies are presumably in Hz; however, the original dataset documentation is not explicit on this point.
activity.type
Activity performed by subject during measurement; 6 levels
WALKING
WALKING_UPSTAIRS
WALKING_DOWNSTAIRS
SITTING
STANDING
LAYING
subject.ID
Subject identification number; 30 levels (i.e., 1 through 30)
t_body.Accel_stdev.X
Standard deviation for X-direction of time domain signal for body acceleration from Accelerometer
t_body.Accel_stdev.Y
Standard deviation for Y-direction of time domain signal for body acceleration from Accelerometer
t_body.Accel_stdev.Z
Standard deviation for Z-direction of time domain signal for body acceleration from Accelerometer
t_grav.Accel_stdev.X
Standard deviation for X-direction of time domain signal for gravity acceleration from Accelerometer
t_grav.Accel_stdev.Y
Standard deviation for Y-direction of time domain signal for gravity acceleration from Accelerometer
t_grav.Accel_stdev.Z
Standard deviation for Z-direction of time domain signal for gravity acceleration from Accelerometer
t_body.Accel.Jerk_stdev.X
Standard deviation for jerk signal X-direction of time domain signal for body acceleration from Accelerometer
t_body.Accel.Jerk_stdev.Y
Standard deviation for jerk signal Y-direction of time domain signal for body acceleration from Accelerometer
t_body.Accel.Jerk_stdev.Z
Standard deviation for jerk signal Z-direction of time domain signal for body acceleration from Accelerometer
t_body.Gyro_stdev.X
Standard deviation for X-direction of time domain signal for body acceleration from Gyroscope
t_body.Gyro_stdev.Y
Standard deviation for Y-direction of time domain signal for body acceleration from Gyroscope
t_body.Gyro_stdev.Z
Standard deviation for Z-direction of time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk_stdev.X
Standard deviation for jerk signal X-direction of time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk_stdev.Y
Standard deviation for jerk signal Y-direction of time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk_stdev.Z
Standard deviation for jerk signal Z-direction of time domain signal for body acceleration from Gyroscope
t_body.Accel.Mag_stdev
Standard deviation of magnitude of time domain signal for body acceleration from Accelerometer
t_grav.Accel.Mag_stdev
Standard deviation of magnitude of time domain signal for gravity acceleration from Accelerometer
t_body.Accel.Jerk.Mag_stdev
Standard deviation of jerk signal magnitude for time domain signal for body acceleration from Accelerometer
t_body.Gyro.Mag_stdev
Standard deviation of magnitude of time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk.Mag_stdev
Standard deviation of jerk signal magnitude for time domain signal for body acceleration from Gyroscope
f_body.Accel_stdev.X
Standard deviation for X-direction when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_stdev.Y
Standard deviation for Y-direction when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_stdev.Z
Standard deviation for Z-direction when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_stdev.X
Standard deviation for jerk signal X-direction when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_stdev.Y
Standard deviation for jerk signal Y-direction when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_stdev.Z
Standard deviation for jerk signal Z-direction when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Gyro_stdev.X
Standard deviation for X-direction when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_stdev.Y
Standard deviation for Y-direction when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_stdev.Z
Standard deviation for Z-direction when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Accel.Mag_stdev
Standard deviation of magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk.Mag_stdev
Standard deviation of jerk signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Gyro.Mag_stdev
Standard deviation of magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro.Jerk.Mag_stdev
Standard deviation of jerk signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
t_body.Accel_mean.X
Mean of X-direction for time domain signal for body acceleration from Accelerometer
t_body.Accel_mean.Y
Mean of Y-direction for time domain signal for body acceleration from Accelerometer
t_body.Accel_mean.Z
Mean of Z-direction for time domain signal for body acceleration from Accelerometer
t_grav.Accel_mean.X
Mean of X-direction for time domain signal for gravity acceleration from Accelerometer
t_grav.Accel_mean.Y
Mean of Y-direction for time domain signal for gravity acceleration from Accelerometer
t_grav.Accel_mean.Z
Mean of Z-direction for time domain signal for gravity acceleration from Accelerometer
t_body.Accel.Jerk_mean.X
Mean jerk signal of X-direction for time domain signal for body acceleration from Accelerometer
t_body.Accel.Jerk_mean.Y
Mean jerk signal of Y-direction for time domain signal for body acceleration from Accelerometer
t_body.Accel.Jerk_mean.Z
Mean jerk signal of Z-direction for time domain signal for body acceleration from Accelerometer
t_body.Gyro_mean.X
Mean of X-direction for time domain signal for body acceleration from Gyroscope
t_body.Gyro_mean.Y
Mean of Y-direction for time domain signal for body acceleration from Gyroscope
t_body.Gyro_mean.Z
Mean of Z-direction for time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk_mean.X
Mean jerk signal of X-direction for time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk_mean.Y
Mean jerk signal of Y-direction for time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk_mean.Z
Mean jerk signal of Z-direction for time domain signal for body acceleration from Gyroscope
t_body.Accel.Mag_mean
Mean magnitude of time domain signal for body acceleration from Accelerometer
t_grav.Accel.Mag_mean
Mean magnitude of time domain signal for gravity acceleration from Accelerometer
t_body.Accel.Jerk.Mag_mean
Mean jerk signal magnitude for time domain signal for body acceleration from Accelerometer
t_body.Gyro.Mag_mean
Mean magnitude of time domain signal for body acceleration from Gyroscope
t_body.Gyro.Jerk.Mag_mean
Mean jerk signal magnitude for time domain signal for body acceleration from Gyroscope
f_body.Accel_mean.X
Mean of X-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_mean.Y
Mean of Y-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_mean.Z
Mean of Z-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_meanFreq.X
Mean frequency of X-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_meanFreq.Y
Mean frequency of Y-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel_meanFreq.Z
Mean frequency of Z-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_mean.X
Mean jerk signal of X-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_mean.Y
Mean jerk signal of Y-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_mean.Z
Mean jerk signal of Z-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_meanFreq.X
Mean frequency of jerk signal of X-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_meanFreq.Y
Mean frequency of jerk signal of Y-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk_meanFreq.Z
Mean frequency of jerk signal of Z-direction for Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Gyro_mean.X
Mean of X-direction for Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_mean.Y
Mean of Y-direction for Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_mean.Z
Mean of Z-direction for Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_meanFreq.X
Mean frequency of X-direction for Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_meanFreq.Y
Mean frequency of Y-direction for Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro_meanFreq.Z
Mean frequency of Z-direction for Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Accel.Mag_mean
Mean magnitude of Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Mag_meanFreq
Mean magnitude of Freq Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk.Mag_mean
Mean jerk signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Accel.Jerk.Mag_meanFreq
Mean frequency of jerk signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Accelerometer
f_body.Gyro.Mag_mean
Mean signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro.Mag_meanFreq
Mean frequency of signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro.Jerk.Mag_mean
Mean jerk signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope
f_body.Gyro.Jerk.Mag_meanFreq
Mean frequency of jerk signal magnitude when Fast Fourier Transform (FFT) applied to body acceleration from Gyroscope jerk signal
angle__t_body.AccelMean_gravMean
Angle between (1) mean time domain signal for body acceleration from Accelerometer (from a sample window) and (2) mean gravity acceleration signal (from a sample window)
angle__t_body.Accel.JerkMean_gravMean
Angle between (1) mean time domain signal for body acceleration from Accelerometer jerk signal (from a sample window) and (2) mean gravity acceleration signal (from a sample window)
angle__t_body.GyroMean_gravMean
Angle between (1) mean time domain signal for body acceleration from Gyroscope (from a sample window) and (2) mean gravity acceleration signal (from a sample window)
angle__t_body.Gyro.JerkMean_gravMean
Angle between (1) mean time domain signal for body acceleration from Gyroscope jerk signal (from a sample window) and (2) mean gravity acceleration signal (from a sample window)
angle__X_gravMean
Angle between (1) X and (2) mean gravity acceleration signal (from a sample window)
angle__Y_gravMean
Angle between (2) Y and (2) mean gravity acceleration signal (from a sample window)
angle__Z_gravMean
Angle between (3) Z and (2) mean gravity acceleration signal (from a sample window)
[1] Davide Anguita, Alessandro Ghio, Luca Oneto, Xavier Parra and Jorge L. Reyes-Ortiz. Human Activity Recognition on Smartphones using a Multiclass Hardware-Friendly Support Vector Machine. International Workshop of Ambient Assisted Living (IWAAL 2012). Vitoria-Gasteiz, Spain. Dec 2012.
Link to Dataset.