oxcar / Coursera_DataScience_getdata_cp

Course Project

Script

The Script is separated among various files:

run_script.R
r_scripts/
|__functions.R
|__features.R
|__train_and_test_data.R
|__merge.R
|__subset.R
|__summarise.R

The main script file is in run_script.R. It sources the R files in r_scripts/ folder and uses the functions declared in those files.

functions.R

Contains functions shared by the rest of R files.

write_data_to_psv_file(data, file_name) :

• Writes the data frame data to file with file name file_name

translate_activity_codes(activity_codes) :

• Reads the activity labels from file and uses them to translate activity_codes
• Returns a vector with the translations.

translate_activity_code(activity_code, activity_labels) :

• Search for activity_code inside activity_labels

features.R

load_features(generate_intermediate_files = FALSE) :

• Reads the features file UCI HAR Dataset//features.txt to a data frame.
• Optionally it saves the features as PSV.
• Returns the features data frame

train_and_test_data.R

load_train_data(features, generate_intermediate_files = FALSE) :

• Reads the train data file UCI HAR Dataset/train/X_train.txt to a data frame.
• Changes the train data frame columns names using the features data frame.
• Reads the activity codes file UCI HAR Dataset/train/y_train.txt and adds a new column activity_code to the train data frame.
• Adds a new column activity_name with the activity_codecolumn translated to text.
• Reads UCI HAR Dataset/train/subject_train.txt and adds a new column subject to the train data frame.
• Optionally it saves train data set to a PSV
• Returns the train data frame.

load_test_data(features, generate_intermediate_files = FALSE) :

• Reads the test data file UCI HAR Dataset/test/X_test.txt to a data frame.
• Changes the test data frame columns names using the features data frame.
• Reads the activity codes file UCI HAR Dataset/test/y_test.txt and adds a new column activity_code to the test data frame.
• Adds a new column activity_name with the activity_codecolumn translated to text.
• Reads UCI HAR Dataset/test/subject_test.txt and adds a new column subject to the test data frame.
• Optionally it saves test data set to a PSV
• Returns the test data frame.

merge.R

merge_train_and_test(train_data, test_data, generate_intermediate_files = TRUE) :

• Merges tran and tes data frames using row binding
• Optionally it saves the merged data frame to PSV

subset.R

subset(data, features, generate_intermediate_files = TRUE) :

• Reads the features data frame and extracts the features with mean() and std() in its names.
• Is selects only the columns with features of mean(), std() and the new columns added in train_and_test_data.R: activity_code, activity_name, subject, train_or_test
• Optionally it saves the new data frame to PSV
• Returns the new data frame

summarise.R

summarise_data(data, generate_intermediate_files = TRUE) :

• Reads data, gorups it by activity and subject, and calculates the mean for every variable, except for the grouped ones.
• Saves the data to file