#Getting and Cleaning Data Course Project Code Book
| Variable Name | Variable Description (units) |
|---|---|
| Activity_Name | The name of the activity being performed during which the measurements were being performed. |
| Subject_ID | The unique, numeric ID assigned to the volunteering subject |
| Body_Acceleration_Mean_X-Axis_Time_Signal | Body Acceleration Mean for the X-Axis (gravity units) |
| Body_Acceleration_Mean_Y-Axis_Time_Signal | Body Acceleration Mean for the Y-Axis (gravity units) |
| Body_Acceleration_Mean_Z-Axis_Time_Signal | Body Acceleration Mean for the Z-Axis (gravity units) |
| Body_Acceleration_Standard_Deviation_X-Axis_Time_Signal | Body Acceleration Standard Deviation for the X-Axis (gravity units) |
| Body_Acceleration_Standard_Deviation_Y-Axis_Time_Signal | Body Acceleration Standard Deviation for the Y-Axis (gravity units) |
| Body_Acceleration_Standard_Deviation_Z-Axis_Time_Signal | Body Acceleration Standard Deviation for the Z-Axis (gravity units) |
| Gravity_Acceleration_Mean_X-Axis_Time_Signal | Gravity Acceleration Mean for the X-Axis (gravity units) |
| Gravity_Acceleration_Mean_Y-Axis_Time_Signal | Gravity Acceleration Mean for the Y-Axis (gravity units) |
| Gravity_Acceleration_Mean_Z-Axis_Time_Signal | Gravity Acceleration Mean for the Z-Axis (gravity units) |
| Gravity_Acceleration_Standard_Deviation_X-Axis_Time_Signal | Gravity Acceleration Standard Deviation for the X-Axis (gravity units) |
| Gravity_Acceleration_Standard_Deviation_Y-Axis_Time_Signal | Gravity Acceleration Standard Deviation for the Y-Axis (gravity units) |
| Gravity_Acceleration_Standard_Deviation_Z-Axis_Time_Signal | Gravity Acceleration Standard Deviation for the Z-Axis (gravity units) |
| Body_Acceleration_Jerk_Mean_X-Axis_Time_Signal | Body Acceleration Jerk Mean for the X-Axis (gravity units) |
| Body_Acceleration_Jerk_Mean_Y-Axis_Time_Signal | Body Acceleration Jerk Mean for the Y-Axis (gravity units) |
| Body_Acceleration_Jerk_Mean_Z-Axis_Time_Signal | Body Acceleration Jerk Mean for the Z-Axis (gravity units) |
| Body_Acceleration_Jerk_Standard_Deviation_X-Axis_Time_Signal | Body Acceleration Jerk Standard Deviation for the X-Axis (gravity units) |
| Body_Acceleration_Jerk_Standard_Deviation_Y-Axis_Time_Signal | Body Acceleration Jerk Standard Deviation for the Y-Axis (gravity units) |
| Body_Acceleration_Jerk_Standard_Deviation_Z-Axis_Time_Signal | Body Acceleration Jerk Standard Deviation for the Z-Axis (gravity units) |
| Body_Gyroscope_Mean_X-Axis_Time_Signal | Body Gyroscope Mean for the X-Axis (radians/second) |
| Body_Gyroscope_Mean_Y-Axis_Time_Signal | Body Gyroscope Mean for the Y-Axis (radians/second) |
| Body_Gyroscope_Mean_Z-Axis_Time_Signal | Body Gyroscope Mean for the Z-Axis (radians/second) |
| Body_Gyroscope_Standard_Deviation_X-Axis_Time_Signal | Body Gyroscope Standard Deviation for the X-Axis (radians/second) |
| Body_Gyroscope_Standard_Deviation_Y-Axis_Time_Signal | Body Gyroscope Standard Deviation for the Y-Axis (radians/second) |
| Body_Gyroscope_Standard_Deviation_Z-Axis_Time_Signal | Body Gyroscope Standard Deviation for the Z-Axis (radians/second) |
| Body_Gyroscope_Jerk_Mean_X-Axis_Time_Signal | Body Gyroscope Jerk Mean for the X-Axis (radians/second) |
| Body_Gyroscope_Jerk_Mean_Y-Axis_Time_Signal | Body Gyroscope Jerk Mean for the Y-Axis (radians/second) |
| Body_Gyroscope_Jerk_Mean_Z-Axis_Time_Signal | Body Gyroscope Jerk Mean for the Z-Axis (radians/second) |
| Body_Gyroscope_Jerk_Standard_Deviation_X-Axis_Time_Signal | Body Gyroscope Jerk Standard Deviation for the X-Axis (radians/second) |
| Body_Gyroscope_Jerk_Standard_Deviation_Y-Axis_Time_Signal | Body Gyroscope Jerk Standard Deviation for the Y-Axis (radians/second) |
| Body_Gyroscope_Jerk_Standard_Deviation_Z-Axis_Time_Signal | Body Gyroscope Jerk Standard Deviation for the Z-Axis (radians/second) |
| Body_Acceleration_Magnitude_Mean_Time_Signal | Body Acceleration Magnitude Mean (gravity units) |
| Body_Acceleration_Magnitude_Standard_Deviation_Time_Signal | Body Acceleration Magnitude Standard Deviation (gravity units) |
| Gravity_Acceleration_Magnitude_Mean_Time_Signal | Gravity Acceleration Magnitude Mean (gravity units) |
| Gravity_Acceleration_Magnitude_Standard_Deviation_Time_Signal | Gravity Acceleration Magnitude Standard Deviation (gravity units) |
| Body_Acceleration_Jerk_Magnitude_Mean_Time_Signal | Body Acceleration Jerk Magnitude Mean (gravity units) |
| Body_Acceleration_Jerk_Magnitude_Standard_Deviation_Time_Signal | Body Acceleration Jerk Magnitude Standard Deviation (gravity units) |
| Body_Gyroscope_Magnitude_Mean_Time_Signal | Body Gyroscope Magnitude Mean (radians/second) |
| Body_Gyroscope_Magnitude_Standard_Deviation_Time_Signal | Body Gyroscope Jerk Magnitude Standard Deviation (radians/second) |
| Body_Gyroscope_Jerk_Magnitude_Mean_Time_Signal | Body Gyroscope Jerk Magnitude Mean (gravity units) |
| Body_Gyroscope_Jerk_Magnitude_Standard_Deviation_Time_Signal | Body Gyroscope Jerk Magnitude Standard Deviation (radians/second) |
| Body_Acceleration_Mean_X-Axis_Frequency_Signal | Body Acceleration Mean for the X-Axis (Hz) |
| Body_Acceleration_Mean_Y-Axis_Frequency_Signal | Body Acceleration Mean for the Y-Axis (Hz) |
| Body_Acceleration_Mean_Z-Axis_Frequency_Signal | Body Acceleration Mean for the Z-Axis (Hz) |
| Body_Acceleration_Standard_Deviation_X-Axis_Frequency_Signal | Body Acceleration Standard Deviation for the X-Axis (Hz) |
| Body_Acceleration_Standard_Deviation_Y-Axis_Frequency_Signal | Body Acceleration Standard Deviation for the Y-Axis (Hz) |
| Body_Acceleration_Standard_Deviation_Z-Axis_Frequency_Signal | Body Acceleration Standard Deviation for the Z-Axis (Hz) |
| Body_Acceleration_Mean_Frequency_X-Axis_Frequency_Signal | Body Acceleration Mean for the X-Axis (Hz) |
| Body_Acceleration_Mean_Frequency_Y-Axis_Frequency_Signal | Body Acceleration Mean for the Y-Axis (Hz) |
| Body_Acceleration_Mean_Frequency_Z-Axis_Frequency_Signal | Body Acceleration Mean for the Z-Axis (Hz) |
| Body_Acceleration_Jerk_Mean_X-Axis_Frequency_Signal | Body Acceleration Jerk Mean for the X-Axis (Hz) |
| Body_Acceleration_Jerk_Mean_Y-Axis_Frequency_Signal | Body Acceleration Jerk Mean for the Y-Axis (Hz) |
| Body_Acceleration_Jerk_Mean_Z-Axis_Frequency_Signal | Body Acceleration Jerk Mean for the Z-Axis (Hz) |
| Body_Acceleration_Jerk_Standard_Deviation_X-Axis_Frequency_Signal | Body Acceleration Jerk Standard Deviatation for the X-Axis (Hz) |
| Body_Acceleration_Jerk_Standard_Deviation_Y-Axis_Frequency_Signal | Body Acceleration Jerk Standard Deviatation for the Y-Axis (Hz) |
| Body_Acceleration_Jerk_Standard_Deviation_Z-Axis_Frequency_Signal | Body Acceleration Jerk Standard Deviatation for the Z-Axis (Hz) |
| Body_Acceleration_Jerk_Mean_Frequency_X-Axis_Frequency_Signal | Body Acceleration Jerk Mean Frequency for the X-Axis (Hz) |
| Body_Acceleration_Jerk_Mean_Frequency_Y-Axis_Frequency_Signal | Body Acceleration Jerk Mean Frequency for the Y-Axis (Hz) |
| Body_Acceleration_Jerk_Mean_Frequency_Z-Axis_Frequency_Signal | Body Acceleration Jerk Mean Frequency for the Z-Axis (Hz) |
| Body_Gyroscope_Mean_X-Axis_Frequency_Signal | Body Gyroscope Mean for the X-Axis (Hz) |
| Body_Gyroscope_Mean_Y-Axis_Frequency_Signal | Body Gyroscope Mean for the Y-Axis (Hz) |
| Body_Gyroscope_Mean_Z-Axis_Frequency_Signal | Body Gyroscope Mean for the Z-Axis (Hz) |
| Body_Gyroscope_Standard_Deviation_X-Axis_Frequency_Signal | Body Gyroscope Standard Deviation for the X-Axis (Hz) |
| Body_Gyroscope_Standard_Deviation_Y-Axis_Frequency_Signal | Body Gyroscope Standard Deviation for the Y-Axis (Hz) |
| Body_Gyroscope_Standard_Deviation_Z-Axis_Frequency_Signal | Body Gyroscope Standard Deviation for the Z-Axis (Hz) |
| Body_Gyroscope_Mean_Frequency_X-Axis_Frequency_Signal | Body Gyroscope Mean Frequency for the X-Axis (Hz) |
| Body_Gyroscope_Mean_Frequency_Y-Axis_Frequency_Signal | Body Gyroscope Mean Frequency for the Y-Axis (Hz) |
| Body_Gyroscope_Mean_Frequency_Z-Axis_Frequency_Signal | Body Gyroscope Mean Frequency for the Z-Axis (Hz) |
| Body_Acceleration_Magnitude_Mean_Frequency_Signal | Body Acceleration Magnitude Standard Deviation (Hz) |
| Body_Acceleration_Magnitude_Standard_Deviation_Frequency_Signal | Body Acceleration Magnitude Standard Deviation (Hz) |
| Body_Acceleration_Magnitude_Mean_Frequency_Frequency_Signal | Body Acceleration Jerk Magnitude Mean (Hz) |
| Body_Acceleration_Jerk_Magnitude_Mean_Frequency_Signal | Body Acceleration Jerk Magnitude Mean (Hz) |
| Body_Acceleration_Jerk_Magnitude_Standard_Deviation_Frequency_Signal | Body Acceleration Jerk Magnitude Standard Deviation (Hz) |
| Body_Acceleration_Jerk_Magnitude_Mean_Frequency_Frequency_Signal | Body Acceleration Jerk Magnitude Mean Frequency (Hz) |
| Body_Gyroscope_Magnitude_Mean_Frequency_Signal | Body Gyroscope Magnitude Mean (Hz) |
| Body_Gyroscope_Magnitude_Standard_Deviation_Frequency_Signal | Body Gyroscope Magnitude Standard Deviation (Hz) |
| Body_Gyroscope_Magnitude_Mean_Frequency_Frequency_Signal | Body Gyroscope Magnitude Mean Frequency (Hz) |
| Body_Gyroscope_Jerk_Magnitude_Mean_Frequency_Signal | Gody Gyroscope Jerk Magnitude Mean (Hz) |
| Body_Gyroscope_Jerk_Magnitude_Standard_Deviation_Frequency_Signal | Body Gyroscope Jerk Magnitude Standard Deviation (Hz) |
| Body_Gyroscope_Jerk_Magnitude_Mean_Frequency_Frequency_Signal | Body Gyroscope Magnitude Mean Frequency (Hz) |
The experiments have been carried out with a group of 30 volunteers within an age bracket of 19-48 years. Each person performed six activities (WALKING, WALKING_UPSTAIRS, WALKING_DOWNSTAIRS, SITTING, STANDING, LAYING) wearing a smartphone (Samsung Galaxy S II) on the waist. Using its embedded accelerometer and gyroscope, we captured 3-axial linear acceleration and 3-axial angular velocity at a constant rate of 50Hz. The experiments have been video-recorded to label the data manually. The obtained dataset has been randomly partitioned into two sets, where 70% of the volunteers was selected for generating the training data and 30% the test data.
The sensor signals (accelerometer and gyroscope) were pre-processed by applying noise filters and then sampled in fixed-width sliding windows of 2.56 sec and 50% overlap (128 readings/window). The sensor acceleration signal, which has gravitational and body motion components, was separated using a Butterworth low-pass filter into body acceleration and gravity. The gravitational force is assumed to have only low frequency components, therefore a filter with 0.3 Hz cutoff frequency was used. From each window, a vector of features was obtained by calculating variables from the time and frequency domain. See 'features_info.txt' for more details.
[Source Dataset](https |//d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip)
See README.md in this directory for an explanation of the process of loading and transforming the data to generate a tidy data set.