Getting and Cleaning Data
INSTRUCTIONS FOR CREATING THE TIDY DATA SET from data collected from the accelerometers from the Samsung Galaxy S smartphone.
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The first task is to unzip the given datafile into a directory, in my case in "C:\Users\Hannu\cleaning" This will create two subdirectories, "test and train", where the actual test and training data is to be found.
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Then the R program "run_analysis.R" should be run with "source". The program requires libraries "data.table" and "reshape2", but they should become loaded automatically. Also the program changes the working directories as needed.
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The purpose is to extract only the measurements on the mean and standard deviation for each measurement and combine the test (2947 observations) and training (7352 observations) data into one dataset. Once this is done there are 82 variables left, 3 of which are for identification purposes and the remaining 79 are the actual data measurements.
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The data will also get averaged by study subject and different activities. Hence in the final tidy data set there are only 180 averages (from 30 subjects and 6 different activities) with 81 (activity number code is redundant) variables left.
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These data are finally printed into a regular text file "tidy_data.txt".