#Codebook
| Variable name | Description |
|---|---|
| subject | ID the subject who performed the activity for each window sample. Its range is from 1 to 30. |
| activity | Activity name |
| featDomain | Feature: Time domain signal or frequency domain signal (Time or Freq) |
| featInstrument | Feature: Measuring instrument (Accelerometer or Gyroscope) |
| featAcceleration | Feature: Acceleration signal (Body or Gravity) |
| featVariable | Feature: Variable (Mean or SD) |
| featJerk | Feature: Jerk signal |
| featMagnitude | Feature: Magnitude of the signals calculated using the Euclidean norm |
| featAxis | Feature: 3-axial signals in the X, Y and Z directions (X, Y, or Z) |
| featCount | Feature: Count of data points used to compute average |
| featAverage | Feature: Average of each variable for each activity and each subject |
str(dtTidy)## Classes 'data.table' and 'data.frame': 11880 obs. of 11 variables:
## $ subject : int 1 1 1 1 1 1 1 1 1 1 ...
## $ activity : Factor w/ 6 levels "LAYING","SITTING",..: 1 1 1 1 1 1 1 1 1 1 ...
## $ featDomain : Factor w/ 2 levels "Time","Freq": 1 1 1 1 1 1 1 1 1 1 ...
## $ featAcceleration: Factor w/ 3 levels NA,"Body","Gravity": 1 1 1 1 1 1 1 1 1 1 ...
## $ featInstrument : Factor w/ 2 levels "Accelerometer",..: 2 2 2 2 2 2 2 2 2 2 ...
## $ featJerk : Factor w/ 2 levels NA,"Jerk": 1 1 1 1 1 1 1 1 2 2 ...
## $ featMagnitude : Factor w/ 2 levels NA,"Magnitude": 1 1 1 1 1 1 2 2 1 1 ...
## $ featVariable : Factor w/ 2 levels "Mean","SD": 1 1 1 2 2 2 1 2 1 1 ...
## $ featAxis : Factor w/ 4 levels NA,"X","Y","Z": 2 3 4 2 3 4 1 1 2 3 ...
## $ count : int 50 50 50 50 50 50 50 50 50 50 ...
## $ average : num -0.0166 -0.0645 0.1487 -0.8735 -0.9511 ...
## - attr(*, "sorted")= chr "subject" "activity" "featDomain" "featAcceleration" ...
## - attr(*, ".internal.selfref")=<externalptr>
key(dtTidy)## [1] "subject" "activity" "featDomain"
## [4] "featAcceleration" "featInstrument" "featJerk"
## [7] "featMagnitude" "featVariable" "featAxis"
dtTidy## subject activity featDomain featAcceleration featInstrument
## 1: 1 LAYING Time NA Gyroscope
## 2: 1 LAYING Time NA Gyroscope
## 3: 1 LAYING Time NA Gyroscope
## 4: 1 LAYING Time NA Gyroscope
## 5: 1 LAYING Time NA Gyroscope
## ---
## 11876: 30 WALKING_UPSTAIRS Freq Body Accelerometer
## 11877: 30 WALKING_UPSTAIRS Freq Body Accelerometer
## 11878: 30 WALKING_UPSTAIRS Freq Body Accelerometer
## 11879: 30 WALKING_UPSTAIRS Freq Body Accelerometer
## 11880: 30 WALKING_UPSTAIRS Freq Body Accelerometer
## featJerk featMagnitude featVariable featAxis count average
## 1: NA NA Mean X 50 -0.01655
## 2: NA NA Mean Y 50 -0.06449
## 3: NA NA Mean Z 50 0.14869
## 4: NA NA SD X 50 -0.87354
## 5: NA NA SD Y 50 -0.95109
## ---
## 11876: Jerk NA SD X 65 -0.56157
## 11877: Jerk NA SD Y 65 -0.61083
## 11878: Jerk NA SD Z 65 -0.78475
## 11879: Jerk Magnitude Mean NA 65 -0.54978
## 11880: Jerk Magnitude SD NA 65 -0.58088
summary(dtTidy)## subject activity featDomain featAcceleration
## Min. : 1.0 LAYING :1980 Time:7200 NA :4680
## 1st Qu.: 8.0 SITTING :1980 Freq:4680 Body :5760
## Median :15.5 STANDING :1980 Gravity:1440
## Mean :15.5 WALKING :1980
## 3rd Qu.:23.0 WALKING_DOWNSTAIRS:1980
## Max. :30.0 WALKING_UPSTAIRS :1980
## featInstrument featJerk featMagnitude featVariable featAxis
## Accelerometer:7200 NA :7200 NA :8640 Mean:5940 NA:3240
## Gyroscope :4680 Jerk:4680 Magnitude:3240 SD :5940 X :2880
## Y :2880
## Z :2880
##
##
## count average
## Min. :36.0 Min. :-0.9977
## 1st Qu.:49.0 1st Qu.:-0.9621
## Median :54.5 Median :-0.4699
## Mean :57.2 Mean :-0.4844
## 3rd Qu.:63.2 3rd Qu.:-0.0784
## Max. :95.0 Max. : 0.9745
dtTidy[, .N, by = c(names(dtTidy)[grep("^feat", names(dtTidy))])]## featDomain featAcceleration featInstrument featJerk featMagnitude
## 1: Time NA Gyroscope NA NA
## 2: Time NA Gyroscope NA NA
## 3: Time NA Gyroscope NA NA
## 4: Time NA Gyroscope NA NA
## 5: Time NA Gyroscope NA NA
## 6: Time NA Gyroscope NA NA
## 7: Time NA Gyroscope NA Magnitude
## 8: Time NA Gyroscope NA Magnitude
## 9: Time NA Gyroscope Jerk NA
## 10: Time NA Gyroscope Jerk NA
## 11: Time NA Gyroscope Jerk NA
## 12: Time NA Gyroscope Jerk NA
## 13: Time NA Gyroscope Jerk NA
## 14: Time NA Gyroscope Jerk NA
## 15: Time NA Gyroscope Jerk Magnitude
## 16: Time NA Gyroscope Jerk Magnitude
## 17: Time Body Accelerometer NA NA
## 18: Time Body Accelerometer NA NA
## 19: Time Body Accelerometer NA NA
## 20: Time Body Accelerometer NA NA
## 21: Time Body Accelerometer NA NA
## 22: Time Body Accelerometer NA NA
## 23: Time Body Accelerometer NA Magnitude
## 24: Time Body Accelerometer NA Magnitude
## 25: Time Body Accelerometer Jerk NA
## 26: Time Body Accelerometer Jerk NA
## 27: Time Body Accelerometer Jerk NA
## 28: Time Body Accelerometer Jerk NA
## 29: Time Body Accelerometer Jerk NA
## 30: Time Body Accelerometer Jerk NA
## 31: Time Body Accelerometer Jerk Magnitude
## 32: Time Body Accelerometer Jerk Magnitude
## 33: Time Gravity Accelerometer NA NA
## 34: Time Gravity Accelerometer NA NA
## 35: Time Gravity Accelerometer NA NA
## 36: Time Gravity Accelerometer NA NA
## 37: Time Gravity Accelerometer NA NA
## 38: Time Gravity Accelerometer NA NA
## 39: Time Gravity Accelerometer NA Magnitude
## 40: Time Gravity Accelerometer NA Magnitude
## 41: Freq NA Gyroscope NA NA
## 42: Freq NA Gyroscope NA NA
## 43: Freq NA Gyroscope NA NA
## 44: Freq NA Gyroscope NA NA
## 45: Freq NA Gyroscope NA NA
## 46: Freq NA Gyroscope NA NA
## 47: Freq NA Gyroscope NA Magnitude
## 48: Freq NA Gyroscope NA Magnitude
## 49: Freq NA Gyroscope Jerk Magnitude
## 50: Freq NA Gyroscope Jerk Magnitude
## 51: Freq Body Accelerometer NA NA
## 52: Freq Body Accelerometer NA NA
## 53: Freq Body Accelerometer NA NA
## 54: Freq Body Accelerometer NA NA
## 55: Freq Body Accelerometer NA NA
## 56: Freq Body Accelerometer NA NA
## 57: Freq Body Accelerometer NA Magnitude
## 58: Freq Body Accelerometer NA Magnitude
## 59: Freq Body Accelerometer Jerk NA
## 60: Freq Body Accelerometer Jerk NA
## 61: Freq Body Accelerometer Jerk NA
## 62: Freq Body Accelerometer Jerk NA
## 63: Freq Body Accelerometer Jerk NA
## 64: Freq Body Accelerometer Jerk NA
## 65: Freq Body Accelerometer Jerk Magnitude
## 66: Freq Body Accelerometer Jerk Magnitude
## featDomain featAcceleration featInstrument featJerk featMagnitude
## featVariable featAxis N
## 1: Mean X 180
## 2: Mean Y 180
## 3: Mean Z 180
## 4: SD X 180
## 5: SD Y 180
## 6: SD Z 180
## 7: Mean NA 180
## 8: SD NA 180
## 9: Mean X 180
## 10: Mean Y 180
## 11: Mean Z 180
## 12: SD X 180
## 13: SD Y 180
## 14: SD Z 180
## 15: Mean NA 180
## 16: SD NA 180
## 17: Mean X 180
## 18: Mean Y 180
## 19: Mean Z 180
## 20: SD X 180
## 21: SD Y 180
## 22: SD Z 180
## 23: Mean NA 180
## 24: SD NA 180
## 25: Mean X 180
## 26: Mean Y 180
## 27: Mean Z 180
## 28: SD X 180
## 29: SD Y 180
## 30: SD Z 180
## 31: Mean NA 180
## 32: SD NA 180
## 33: Mean X 180
## 34: Mean Y 180
## 35: Mean Z 180
## 36: SD X 180
## 37: SD Y 180
## 38: SD Z 180
## 39: Mean NA 180
## 40: SD NA 180
## 41: Mean X 180
## 42: Mean Y 180
## 43: Mean Z 180
## 44: SD X 180
## 45: SD Y 180
## 46: SD Z 180
## 47: Mean NA 180
## 48: SD NA 180
## 49: Mean NA 180
## 50: SD NA 180
## 51: Mean X 180
## 52: Mean Y 180
## 53: Mean Z 180
## 54: SD X 180
## 55: SD Y 180
## 56: SD Z 180
## 57: Mean NA 180
## 58: SD NA 180
## 59: Mean X 180
## 60: Mean Y 180
## 61: Mean Z 180
## 62: SD X 180
## 63: SD Y 180
## 64: SD Z 180
## 65: Mean NA 180
## 66: SD NA 180
## featVariable featAxis N
Save data table objects to a space-delimited text file called human-activity-recognition-using-smartphones.txt.
tidyFile <- file.path(path, "human-activity-recognition-using-smartphones.txt")
write.table(dtTidy, tidyFile, row.names = FALSE)