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CodeBook

Intro / Summary of Data Description and Analysis

Data Set and Description

Original Data Description: http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones

Original Data Source: https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip

Variables Used and Modified

The data used in this archive were both the test and training sets.

  • X_train, X_test - were merged together
  • y_test ,y_train - were merged together
  • subject_train, subject_test - were merged together These datasets above were merged using rbind() and cbind. This formed a 10299 by 69 tidied dataset after steps 1-4 were completed

activity_labels.txt

Activity ID and Labels were used and merged into the new master dataset generated

  • 1 WALKING
  • 2 WALKING_UPSTAIRS
  • 3 WALKING_DOWNSTAIRS
  • 4 SITTING
  • 5 STANDING
  • 6 LAYING

features.txt - Defined the column index and variable name(s) of the test and training data mentioned above

Only variables that were named with mean(-mean() and standard deviation( -std() ) were extracted from the data set. There should be 69 total variable, 66 are mean or standard deviation data

The following are example names that were extracted from the original set of 561 variables:

  • 3 tBodyAcc-mean()-Z
  • 4 tBodyAcc-std()-X
  • ...
  • 268 fBodyAcc-mean()-Z
  • 269 fBodyAcc-std()-X
  • ...

Variable names were also modified from the source in the following manner:

  • f - Variables starting with "f" were replaced with freq
  • t - Variables starting with "t" were replaced with time
  • Acc - were substituted with Accelerator
  • Mag - were substituted with Magnitude
  • Gyro - were substituted with Gyrometer
  • "-" - were substituted with "_"

Tidy Data Set

  • The tidy.txt data set was generated from the above dataset and had an aggregate function applied to each activity for each subject(person).
  • The results of this aggregate data were sorted by subject and then sorted by activity.
  • This tidy data is written to tidy.txt file
  • There are 180 observations of the mean-calculated data per activity, per person.

Variables Not Used

No Inertial Signal data were used from this archive in this analysis