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CodeBook.md

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Getting and Cleaning Data: course project CodeBook

The final project summarizes and tidy the data into a table exported in the file output.txt. This document is the Code Book for the summarized data.

The summarized data reports the average and standard deviation values of the various acceleromenter data sources, grouped by the subject that performed the test and the activity that was manually labeled corresponding to that data set.

The data set was meant to be used in a Machine Learning competition/set up, so it is defined in terms of features and labels, and it was split into a train and test set.

As a part of this analysis, all data was gathered and analyzed together.

Here following the full explanation of the 68 columns names and meaning:

  • subject the subject ID that performed the test. Served as a factor, since numerical value doesn't really make sense
  • activity the readable activity label assigned manually to the user performing the test

All the columns starting with "t" denote raw values sampled at a 50 hz frequency

  • tbodyacc.mean.x mean accelerometer data of the body over x
  • tbodyacc.mean.y mean accelerometer data of the body over y
  • tbodyacc.mean.z mean accelerometer data of the body over z
  • tbodyacc.std.x stddev of accelerometer data of the body over x
  • tbodyacc.std.y stddev of accelerometer data of the body over y
  • tbodyacc.std.z stddev of accelerometer data of the body over z
  • tgravityacc.mean.x mean gravity accel over x
  • tgravityacc.mean.y mean gravity accel over y
  • tgravityacc.mean.z mean gravity accel over z
  • tgravityacc.std.x stddev of gravity accel over x
  • tgravityacc.std.y stddev of gravity accel over y
  • tgravityacc.std.z stddev of gravity accel over z
  • tbodyaccjerk.mean.x (not really sure if it makes sense to go on)
  • tbodyaccjerk.mean.y [...]
  • tbodyaccjerk.mean.z [...]
  • tbodyaccjerk.std.x [...]
  • tbodyaccjerk.std.y [...]
  • tbodyaccjerk.std.z [...]
  • tbodygyro.mean.x [...]
  • tbodygyro.mean.y [...]
  • tbodygyro.mean.z [...]
  • tbodygyro.std.x [...]
  • tbodygyro.std.y [...]
  • tbodygyro.std.z [...]
  • tbodygyrojerk.mean.x [...]
  • tbodygyrojerk.mean.y [...]
  • tbodygyrojerk.mean.z [...]
  • tbodygyrojerk.std.x [...]
  • tbodygyrojerk.std.y [...]
  • tbodygyrojerk.std.z [...]
  • tbodyaccmag.mean. [...]
  • tbodyaccmag.std. [...]
  • tgravityaccmag.mean. [...]
  • tgravityaccmag.std. [...]
  • tbodyaccjerkmag.mean. [...]
  • tbodyaccjerkmag.std. [...]
  • tbodygyromag.mean. [...]
  • tbodygyromag.std. [...]
  • tbodygyrojerkmag.mean. [...]
  • tbodygyrojerkmag.std. [...]

All the columns starting with "f" denote frequency values computed via Fast Fourier Transform

  • fbodyacc.mean.x [...]
  • fbodyacc.mean.y [...]
  • fbodyacc.mean.z [...]
  • fbodyacc.std.x [...]
  • fbodyacc.std.y [...]
  • fbodyacc.std.z [...]
  • fbodyaccjerk.mean.x [...]
  • fbodyaccjerk.mean.y [...]
  • fbodyaccjerk.mean.z [...]
  • fbodyaccjerk.std.x [...]
  • fbodyaccjerk.std.y [...]
  • fbodyaccjerk.std.z [...]
  • fbodygyro.mean.x [...]
  • fbodygyro.mean.y [...]
  • fbodygyro.mean.z [...]
  • fbodygyro.std.x [...]
  • fbodygyro.std.y [...]
  • fbodygyro.std.z [...]
  • fbodyaccmag.mean. [...]
  • fbodyaccmag.std. [...]
  • fbodybodyaccjerkmag.mean. [...]
  • fbodybodyaccjerkmag.std. [...]
  • fbodybodygyromag.mean. [...]
  • fbodybodygyromag.std. [...]
  • fbodybodygyrojerkmag.mean. [...]
  • fbodybodygyrojerkmag.std. [...]