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Primary LanguageR

This is the description file for the Peer-graded Assignment: Getting and Cleaning Data Course Project

The run_analysis.R script is used to tidy the original Samsung dataset given in the assigment.

In the script there are several steps, following the steps given in the assigment:

  • Step 1: Merges the training and the test sets to create one data set. I read both, train and test, datasets together with their activities files and combined them by rows to create one dataset
  • Step 2: Extracts only the measurements on the mean and standard deviation for each measurement. I read the features file and grep those features than contains the mean and std function in their names
  • Step 3: Uses descriptive activity names to name the activities in the data set. The activities in the original dataset where coded using numbers, but using the activity_labels file I was able to transform those numbers into descriptive activity names
  • Step 4: Appropriately labels the data set with descriptive variable names. In order to relabel the variables in the dataset I removed the brackets and used an underscore to replace the dashed, also I tranformed the initial "t" and "f" for "Time" and "Freq" respectively, making the labels to be more self-explanatory to everyone. Althought it is not specified in any of the previous steps I added the subjects information to the dataset because it will be used in the last step.

The dataset obtained after these 4 steps was saved in tidy_dataset.txt and was submitted together with this assigment.

  • Step 5: From the data set in step 4, creates a second, independent tidy data set with the average of each variable for each activity and each subject. In this step, I grouped the dataset by activity and subject, and them summarise all the variables in each group using their means.

Code book

Dataset
Human Activity Recognition Using Smartphones Dataset
Version 1.0
Tidied by me :D

In the dataset we have the mean and standard deviation of the time and frequency of several measurements for 30 individuals regarding 6 different activities.

  • Number of individuals: 30 (from individual 1 to 30)
  • Activities: 6 (WALKING, WALKING_UPSTAIRS, WALKING_DOWNSTAIRS, SITTING, STANDING, LAYING)
  • Meassurements: Some meassurements were meassured for the 3 spatial axis (X, Y and Z) such as, body acceleration; and others were meassured in general, like gravity

So for each record it is provided:

  • Its activity label.
  • An identifier of the subject who carried out the experiment.
  • 66 meassurements cited above