bladeralien / gettingandcleaningdata_courseproject

Getting And Cleaning Data: Course Project

Merges the training and the test sets to create one data set.

After downloading and reading in raw datasets, i use cbind and rbind to combine the following six files.

• train/subject_train.txt
• train/X_train.txt
• train/y_train.txt
• test/subject_test.txt
• test/X_test.txt
• test/y_test.txt

I did not include a seperate column for data source (i.e., train/test), because it can be telled from subject id.

Extracts only the measurements on the mean and standard deviation for each measurement.

I only keep columns with "mean()" and "std()", that results 33*2=66 colomns.

Uses descriptive activity names to name the activities in the data set.

It can be easily done by replace activity id from file "train/y_train.txt" and "test/y_test.txt" by labels from file "activity_labels.txt".

Appropriately labels the data set with descriptive variable names.

I think names like "fBodyBodyGyroJerkMag-mean()" is descriptive enough, and also quite long already, and there is not need to expand it. I just remove "-" and "()" and capitalize word "mean" and "std".

From the data set in step 4, creates a second, independent tidy data set with the average of each variable for each activity and each subject.

This can be done with function "summarise_each" from "dplyr" package.