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This file explains how Run_Analysis.R works in order to produce a tidy data set from
http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones
Data for the proyect can be retrieved at https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip
The script works as follows:
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Load Data into R
Read Files under directory UCI HAR Dataset
Read different variables: Activity (Test and Train), Subject (Test and Train) Features (Test and Train)
Concatenate the data_tables train + test by rows regarding subject, activity and features
Set descriptive names to variables
Obtain unique column_ids for "select" in dplyr -
Merges the training and the test sets to create one data set
Merges Activity, Subject and Features data sets by column -
Extracts only the measurements on the mean and standard deviation for each measurement.
Filter columns to get the data for mean(), std(), activity, subject -
Uses descriptive activity names to name the activities in the data set
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Appropriately labels the data set with descriptive variable names
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Creates a second,independent tidy data set and ouput it
First aggregate data to calculate mean by (subject & activity variables)
Second arrange data by subject and activity
Third wirte output totidydata.txt