title	author	date	output
README	Xiaoyun Yang	Thursday, May 21, 2015	html_document

Step 1:Reading

read.table is used to read the .txt file as R objects

Step 2:Merging

I used the rbind command to merge the data since there are no repetitive subjects between train and test data sets and this will save some processing time also.

Step 3:Extraction

grep function is used to select the columns with variables which contain "mean" or "std";

Step 4:Rename

Rename the variable with descriptive name given in feature.txt; convert the activity code into activity labels

Step 5:Attach

Attach the subject and activity column to the data set

Step 6:Average

Average each variable grouped by subject and activity

Step 7:Remove

Remove extra columns introduced by aggregate function

step 8:Write

Write the data set to .txt file