Code Book

Introduction

The script run_analysis.R performs the 5 steps described in the course project's definition.

First, all the similar data is merged using the rbind() function. By similar, we address those files having the same number of columns and referring to the same entities.
Then, only those columns with the mean and standard deviation measures are taken from the whole dataset. After extracting these columns, they are given the correct names, taken from features.txt.
As activity data is addressed with values 1:6, we take the activity names and IDs from activity_labels.txt and they are substituted in the dataset.
On the whole dataset, those columns with vague column names are corrected.
Finally, we generate a new dataset with all the average measures for each subject and activity type (30 subjects * 6 activities = 180 rows).

The output file is called tidy_avg_data.txt, and uploaded to this repository.

x_train, y_train, x_test, y_test, subject_train and subject_test contain the data from the downloaded files.
x_data, y_data and subject_data merge the previous datasets to further analysis.
features contains the correct names for the x_data dataset, which are applied to the column names stored in meanstd_features, a numeric vector used to extract the desired data.
A similar approach is taken with activity names through the activities variable.
all_data merges x_data, y_data and subject_data in a big dataset.
Finally, tidy_average_data contains the relevant averages which will be later stored in a .txt file. The melt() function from the reshape2 package is used to create the average of each activity and each subject.

subject - The ID of the test subject
activity - The type of activity performed when the corresponding measurements were taken

WALKING (value 1): subject was walking during the test
WALKING_UPSTAIRS (value 2): subject was walking up a staircase during the test
WALKING_DOWNSTAIRS (value 3): subject was walking down a staircase during the test
SITTING (value 4): subject was sitting during the test
STANDING (value 5): subject was standing during the test
LAYING (value 6): subject was laying down during the test