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The file "Subject_Activity_Average.txt" contains a table with 36 rows and 67 columns. Following is the list of of columns/fields. Each row represents an pbservation - either the subject or activity for which the remaining variables are averaged.
1. Group (Subject/Activity) - The variable by which the data is grouped and averaged for. It consists of 36 groups :
30 subjects - numbered 1 to 30.
6 activities - Walking, Walking Upstairs, Walking Downstairs, Sitting, Standing and Laying.
Columns 2-67 represent the measurements under consideration in the study. Each column name is the name of the variable measured (either mean or std) and the value in each row is the average value of that variable for the group corresponding to that row. The following measures are dervied from linear accleration signals measured by an accelerometer (Acc) and angular velocity signals measured by a gyroscope (Gyro), in time. Linear acceleration was divided into body acceleration and gravity acceleration. The time domain signals were converted to frequency domain signals by Fast Fourier transform (FFT).
2. tBodyAcc-mean()-X - Mean of the time domain body acceleration signals measured in the X-direction.
3. tBodyAcc-mean()-Y - Mean of the time domain body acceleration signals measured in the Y-direction
4. tBodyAcc-mean()-Z - Mean of the time domain body acceleration signals measured in the Z-direction
5. tBodyAcc-std()-X - Standard deviation of the time domain body acceleration signals measured in the X-direction
6. tBodyAcc-std()-Y - Standard deviation of the time domain body acceleration signals measured in the Y-direction
7. tBodyAcc-std()-Z - Standard deviation of the time domain body acceleration signals measured in the Z-direction
8. tGravityAcc-mean()-X - Mean of the time domain of the gravity acceleration signals measured in the X-direction
9. tGravityAcc-mean()-Y - Mean of the time domain of the gravity acceleration signals measured in the Y-direction
10. tGravityAcc-mean()-Z - Mean of the time domain of the gravity acceleration signals measured in the Z-direction
11. tGravityAcc-std()-X - Standard deviation of the time domain of the gravity acceleration signals measured in the X-direction
12. tGravityAcc-std()-Y - Standard deviation of the time domain of the gravity acceleration signals measured in the Y-direction
13. tGravityAcc-std()-Z - Standard deviation of the time domain of the gravity acceleration signals measured in the Z-direction
14. tBodyAccJerk-mean()-X - Mean of the time domain of jerk signals from linear acceleration measured in the X-direction
15. tBodyAccJerk-mean()-Y - Mean of the time domain of jerk signals from linear acceleration measured in the Y-direction
16. tBodyAccJerk-mean()-Z - Mean of the time domain of jerk signals from linear acceleration measured in the Z-direction
17. tBodyAccJerk-std()-X - Standard deviation of the time domain of jerk signals from linear acceleration measured in the X-direction
18. tBodyAccJerk-std()-Y - Standard deviation of the time domain of jerk signals from linear acceleration measured in the Y-direction
19. tBodyAccJerk-std()-Z - Standard deviation of the time domain of jerk signals from linear acceleration measured in the Z-direction
20. tBodyGyro-mean()-X - Mean of the time domain of angular velocity measured in the X-direction
21. tBodyGyro-mean()-Y - Mean of the time domain of angular velocity measured in the Y-direction
22. tBodyGyro-mean()-Z - Mean of the time domain of angular velocity measured in the Z-direction
23. tBodyGyro-std()-X - Standard deviation of the time domain of angular velocity measured in the X-direction
24. tBodyGyro-std()-Y - Standard deviation of the time domain of angular velocity measured in the Y-direction
25. tBodyGyro-std()-Z - Standard deviation of the time domain of angular velocity measured in the Z-direction
26. tBodyGyroJerk-mean()-X - Mean of the time domain of jerk signals from angular velocity measured in the X-direction
27. tBodyGyroJerk-mean()-Y - Mean of the time domain of jerk signals from angular velocity measured in the Y-direction
28. tBodyGyroJerk-mean()-Z - Mean of the time domain of jerk signals from angular velocity measured in the Z-direction
29. tBodyGyroJerk-std()-X - Standard deviation of the time domain of jerk signals from angular velocity measured in the X-direction
30. tBodyGyroJerk-std()-Y - Standard deviation of the time domain of jerk signals from angular velocity measured in the Y-direction
31. tBodyGyroJerk-std()-Z - Standard deviation of the time domain of jerk signals from angular velocity measured in the Z-direction
32. tBodyAccMag-mean() - Mean of the magnitude of the time domain of body acceleration calculated by Euclidean norm
33. tBodyAccMag-std() - Standard deviation of the magnitude of the time domain of body acceleration calculated by Euclidean norm
34. tGravityAccMag-mean() - Mean of the magnitude of the time domain of gravity acceleration calculated by Euclidean norm
35. tGravityAccMag-std() - Standard deviaion of the magnitude of the time domain of gravity acceleration calculated by Euclidean norm
36. tBodyAccJerkMag-mean() - Mean of the magnitude of the time domain of jerk signals from linear acceleration calculated by Euclidean norm
37. tBodyAccJerkMag-std() - Standard deviation of the magnitude of the time domain of jerk signals from linear acceleration calculated by Euclidean norm
38. tBodyGyroMag-mean() - Mean of the magnitude of the time domain of angular velocity calculated by Euclidean norm
39. tBodyGyroMag-std() - Standard deviation of the magnitude of the time domain of angular velocity calculated by Euclidean norm
40. tBodyGyroJerkMag-mean() - Mean of the magnitude of the time domain of jerk signals from angular velocity calculated by Euclidean norm
41. tBodyGyroJerkMag-std() - Standard deviation of the magnitude of the time domain of jerk signals from angular velocity calculated by Euclidean norm
42. fBodyAcc-mean()-X - Mean of the frequency domain body acceleration signals measured in the X-direction
43. fBodyAcc-mean()-Y - Mean of the frequency domain body acceleration signals measured in the Y-direction
44. fBodyAcc-mean()-Z Mean of the frequency domain body acceleration signals measured in the Z-direction
45. fBodyAcc-std()-X - Standard deviation of the frequency domain body acceleration signals measured in the X-direction
46. fBodyAcc-std()-Y - Standard deviation of the frequency domain body acceleration signals measured in the Y-direction
47. fBodyAcc-std()-Z - Standard deviation of the frequency domain body acceleration signals measured in the Z-direction
48. fBodyAccJerk-mean()-X - Mean of the frequency domain of jerk signals from linear acceleration signals measured in the X-direction
49. fBodyAccJerk-mean()-Y - Mean of the frequency domain of jerk signals from linear acceleration signals measured in the Y-direction
50. fBodyAccJerk-mean()-Z - Mean of the frequency domain of jerk signals from linear acceleration signals measured in the Z-direction
51. fBodyAccJerk-std()-X - Standard deviation of the frequency domain of jerk signals from linear acceleration signals measured in the X-direction
52. fBodyAccJerk-std()-Y - Standard deviation of the frequency domain of jerk signals from linear acceleration signals measured in the Y-direction
53. fBodyAccJerk-std()-Z - Standard deviation of the frequency domain of jerk signals from linear acceleration signals measured in the Z-direction
54. fBodyGyro-mean()-X - Mean of the frequency domain of jerk signals from angular velocity signals measured in the X-direction
55. fBodyGyro-mean()-Y - Mean of the frequency domain of jerk signals from angular velocity signals measured in the Y-direction
56. fBodyGyro-mean()-Z - Mean of the frequency domain of jerk signals from angular velocity signals measured in the Z-direction
57. fBodyGyro-std()-X - Standard deviation of the frequency domain of jerk signals from angular velocity signals measured in the X-direction
58. fBodyGyro-std()-Y - Standard deviation of the frequency domain of jerk signals from angular velocity signals measured in the Y-direction
59. fBodyGyro-std()-Z- Standard deviation of the frequency domain of jerk signals from angular velocity signals measured in the Z-direction
60. fBodyAccMag-mean() - Mean of the magnitude of the frequency domain of linear acceleration calculated by Euclidean norm
61. fBodyAccMag-std() - Standard deviation of the magnitude of the frequency domain of linear acceleration calculated by Euclidean norm
62. fBodyBodyAccJerkMag-mean() - Mean of the magnitude of the frequency domain of jerk signals from linear acceleration calculated by Euclidean norm
63. fBodyBodyAccJerkMag-std() - Standard deviation of the magnitude of the frequency domain of jerk signals from linear acceleration calculated by Euclidean norm
64. fBodyBodyGyroMag-mean() - Mean of the magnitude of the frequency domain of angular velocity calculated by Euclidean norm
65. fBodyBodyGyroMag-std() - Standard deviation of the magnitude of the frequency domain of angular velocity calculated by Euclidean norm
66. fBodyBodyGyroJerkMag-mean() - Mean of the magnitude of the frequency domain of jerk signals from angular velocity calculated by Euclidean norm
67. fBodyBodyGyroJerkMag-std() - Standard deviation of the magnitude of the frequency domain of jerk signals from angular velocity calculated by Euclidean norm