code_book

the first data.frame that is created is called df_no_average and has 10299 rows (7352 rows from the "train" directory and 
2947 from the "test" directory, where each of the rows is one observation) and 69 columns. The first column is called
"Number_Subject" and contains the number corresponding to the person who was taking part in the study for this observation.
The 2nd column is called "Activity_description" and contains a descriptive name of the activity (WALKING, WALKING_UPSTAIRS...).
The 3rd column is called "train_or_test" and contains either "Train" or "Test", depending from which directory the observation
was taken. The 4th through 69th columns contain values for the 66 variables containing either "mean()" or "std()" in their names.

the 2nd data.frame that was created is called df_average and has 11880 rows and 4 columns. The columns are:
1. "Number_Subject": contains the number corresponding to the person who was taking part in the study for this observation
2. "Activity": contains a descriptive name of the activity (WALKING, WALKING_UPSTAIRS...)
3. "Variable": contains a descriptive name of the variable
4. "Value": contains the average value of the variable for the given person and for the given activity

the rows are all the possible combinations of the three columns in the beginning.