Run_Analysis.R

Author: SUSM

Diff for: Run_analysis.R

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+
+setwd(""C:/Users/SUSM/Documents/assignmentdata/UCI HAR Dataset")
+
+list.files("./test")						
+
+###step1: Merge the Test and Train data sets to create merged data sets of Test and Train
+
+TestX<-read.table("./test/X_test.txt") 			
+TestY<-read.table("./test/y_test.txt") 			
+Testsubject<-read.table("./test/subject_test.txt")	
+
+list.files("./train")						
+
+TrainX<-read.table("./Train/X_train.txt")			
+TrainY<-read.table("./Train/y_train.txt")			
+Trainsubject<-read.table("./Train/subject_train.txt")	
+
+mergedX<-rbind(TestX,TrainX)					## rowbind Test and Training sets to create mergedX dataset
+mergedY<-rbind(TestY,TrainY)					
+mergedsubject<-rbind(Testsubject,Trainsubject)		
+
+## step2: Extract only the measurements of only mean and standard deviation 
+
+
+features<-read.table("features.txt")			## read features.txt file into features data frame
+
+									## using grep(),extract variables ending with mean() and std() from features dataset  
+									## and assign to features_meanstd subset
+features_meanstd<-features[grep("mean\\>|std",features$V2),]
+
+
+## step 3: and label the data with descriptive variable names									
+features_meanstd[,2]<-sub("tB","timeB",features_meanstd[,2])
+features_meanstd[,2]<-sub("tG","timeG",features_meanstd[,2])
+									
+features_meanstd[,2]<-sub("f","Freq",features_meanstd[,2])
+									## find and replace illegal characters with '.' in the variable names of dataset
+features_meanstd[,2]<-gsub("[()]","",features_meanstd[,2])
+features_meanstd[,2]<-gsub("-",".",features_meanstd[,2])
+
+									
+mergedXmeanstd<-mergedX[,c(features_meanstd[,1])]
+									
+names(mergedXmeanstd)<-c(features_meanstd[,2])		## rename column names with descriptive variable names assigned in features_meanstd
+
+## step 4: descriptive activity names to name the activities in the data
+
+names(mergedY)<-c("Activity")					## rename column name to Activity in mergedY dataset
+names(mergedsubject)<-c("Subject")				## rename column name to Subject in mergedsubject dataset
+
+activity_labels<-read.table("activity_labels.txt")	
+activitylabels<-activity_labels[,2]				
+mergedY$Activity<-as.factor(mergedY$Activity)
+mergedY$Activity<-factor(mergedY$Activity,labels=activitylabels)
+
+									## cbind X data (containing mean & std),Y and subject datasets to create one mergeddata data set
+mergeddata<-cbind(mergedsubject,mergedY,mergedXmeanstd)
+
+## step5: create tidy data set from the one data set created above
+
+library(reshape2)							
+									
+
+melteddata<-melt(mergeddata, id.vars=c("Subject","Activity"),measure.vars=c(features_meanstd[,2]))
+									
+casteddata<-dcast(melteddata,Subject+Activity ~ variable, mean)
+
+## write the casteddata into tidydata.txt file using write.table
+
+write.table(castdata,file="tidydata.txt", sep="\t", row.name=FALSE)