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The script run_analysis.R , downloads the file https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip and saves in the working directory as wearable.zip and unzips it.
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The script ignores the raw data files in the directories "UCI HAR Dataset/train/Inertial Signals" and "UCI HAR Dataset/test/Inertial Signals"
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The script then reads data from featurs.txt and activity_labels.txt
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Only the features that contain the string -mean() or -std() in the feature name are selected
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The names of the features are modified to a. Convert the uppercase characters to lowercase b. Remove the characters - ( )
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The script then reads data from X_train.txt ,y_train.txt ,subject_train.txt . It reads only the columns selected in step 4 from the file X_train
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The script then reads data from X_test.txt ,y_test.txt ,subject_test.txt . It reads only the columns selected in step 4 from the file X_test
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The script combines rows from y_train.txt and y_test.txt into "y_all" data frame
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The script combines rows from subject_train.txt and subject_test.txt into "subject" data frame
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The script merges y_all and subject data frames into "adt" data frame
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The script combines rows from x_train.txt and x_test.txt into "x_data" data frame
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The script then merges data frames "adt" and "activity_labels" into "activity" data frame
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The script then combines columns from x_data and activity into data frame "all_data"
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The script removes column activityid from the dataframe "all_data"
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The script then creates a second, independent tidy data set "data_ave_by_subject_activity" with the average of each variable for each activity and each subject
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The script then writes the new tidy dataset into file tidydata.txt in to working directory