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Data Dictionary -- Human Activity Recognition Using Smartphones Dataset

subject: subject ID

activity: activity subject was performing while wearing the smartphone

  • laying (6): subject was laying while measurements were taken
  • sitting (4): subject was sitting while measurements were taken
  • standing (5): subject was standing while measurements were taken
  • walking (1): subject was walking while measurements were taken
  • walkingup (2): subject was walking upstairs while measurements were taken
  • walkingdown (3): subject was walking downstairs while measurements were taken

Note: in original dataset, activities corresponded to numbers (found in activity_labels.txt) -- original number labels are in parentheses after activity name

Features:

  • time: time domain signals (captured at a constant rate of 50 Hz)
  • freq: frequency domain signals
  • Body: body signal
  • Gravity: gravitational signal
  • Acc: signal from accelerometer
  • Gyro: signal from gyroscope (radians/second)
  • Jerk: body linear acceleration and angular velocity derived in time
  • Mag: magnitude of the three-dimensional signals (calculated using the Euclidean norm)
  • mean: mean value
  • std: standard deviation value
  • X: axial signal in the X direction
  • Y: axial signal in the Y direction
  • Z: axial signal in the Z direction

Note: in the tidy data set, all measurements are means Note: all features are normalized and bounded within [-1,1], as in original dataset

e.g.: "timeBodyAcc.mean.X" represents the mean of the mean of time domain body signal from the accelerometer in the X direction

"freqBodyGyroMag.std" represents the mean of the standard deviation of magnitude of the frequency domain body signals from the gyroscope

List of all features:

  • timeBodyAcc.mean.X
  • timeBodyAcc.mean.Y
  • timeBodyAcc.mean.Z
  • timeBodyAcc.std.X
  • timeBodyAcc.std.Y
  • timeBodyAcc.std.Z
  • timeGravityAcc.mean.X
  • timeGravityAcc.mean.Y
  • timeGravityAcc.mean.Z
  • timeGravityAcc.std.X
  • timeGravityAcc.std.Y
  • timeGravityAcc.std.Z
  • timeBodyAccJerk.mean.X
  • timeBodyAccJerk.mean.Y
  • timeBodyAccJerk.mean.Z
  • timeBodyAccJerk.std.X
  • timeBodyAccJerk.std.Y
  • timeBodyAccJerk.std.Z
  • timeBodyGyro.mean.X
  • timeBodyGyro.mean.Y
  • timeBodyGyro.mean.Z
  • timeBodyGyro.std.X
  • timeBodyGyro.std.Y
  • timeBodyGyro.std.Z
  • timeBodyGyroJerk.mean.X
  • timeBodyGyroJerk.mean.Y
  • timeBodyGyroJerk.mean.Z
  • timeBodyGyroJerk.std.X
  • timeBodyGyroJerk.std.Y
  • timeBodyGyroJerk.std.Z
  • timeBodyAccMag.mean
  • timeBodyAccMag.std
  • timeGravityAccMag.mean
  • timeGravityAccMag.std
  • timeBodyAccJerkMag.mean
  • timeBodyAccJerkMag.std
  • timeBodyGyroMag.mean
  • timeBodyGyroMag.std
  • timeBodyGyroJerkMag.mean
  • timeBodyGyroJerkMag.std
  • freqBodyAcc.mean.X
  • freqBodyAcc.mean.Y
  • freqBodyAcc.mean.Z
  • freqBodyAcc.std.X
  • freqBodyAcc.std.Y
  • freqBodyAcc.std.Z
  • freqBodyAccJerk.mean.X
  • freqBodyAccJerk.mean.Y
  • freqBodyAccJerk.mean.Z
  • freqBodyAccJerk.std.X
  • freqBodyAccJerk.std.Y
  • freqBodyAccJerk.std.Z
  • freqBodyGyro.mean.X
  • freqBodyGyro.mean.Y
  • freqBodyGyro.mean.Z
  • freqBodyGyro.std.X
  • freqBodyGyro.std.Y
  • freqBodyGyro.std.Z
  • freqBodyAccMag.mean
  • freqBodyAccMag.std
  • freqBodyAccJerkMag.mean
  • freqBodyAccJerkMag.std
  • freqBodyBodyGyroMag.mean
  • freqBodyGyroMag.std
  • freqBodyGyroJerkMag.mean
  • freqBodyGyroJerkMag.std

Note: feature names were changed from original dataset by removing parentheses, substituting dashes (-) with periods (.), and expanding "t" and "f" to "time" and "frequency"