For creating a tidy data set of wearable computing data originally from http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones
- README.md -- This document
- CodeBook.md -- Codebook describing variables, the data and transformations
- run_analysis.R -- R code for tidying data
You should create one R script called run_analysis.R that does the following:
- Merges the training and the test sets to create one data set.
- Extracts only the measurements on the mean and standard deviation for each measurement.
- Uses descriptive activity names to name the activities in the data set
- Appropriately labels the data set with descriptive activity names.
- Creates a second, independent tidy data set with the average of each variable for each activity and each subject.
You may download source file from: https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip, then extract zip to the working directory. If R program detect the folder doesn't exist, it will download file automatically.
The output is created in working directory with the name of tidy_data.txt
Note: the R script is built to run without including any libraries for the purpose of this course.
It follows the goals step by step.
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Step 1:
- Check UCI HAR Dataset folder existence; if not, download file and unzip it.
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Step 2:
- Read all test and training files.
- Combine training and test data for subject, x, y.
-
Step 3:
- Read all features from features.txt and filter it to only leave features that are either means ("mean()") or standard deviations ("std()").
- Also, using previous filtering rule to label each column name of features.
-
Step 4:
- Read the activity labels from activity_labels.txt and replace the numbers with the text by
merge()
function.
- Read the activity labels from activity_labels.txt and replace the numbers with the text by
-
Step 5:
- Using
cbind()
to merge subject, activity, and filtered features. - Label subject and activity column.
- Using
-
Step 6:
- Write the new tidy set into a text file called tidy_data.txt.