Read file marks1.csv
setwd('C:/Users/Administrator/Desktop')
marks1 <- read.csv(file = 'marks1.csv',head=TRUE,sep=',')
marks1## X X.1 test asgn Prsnt Final q1 q2 q3 q4
## 1 60001 Ahmad 15 14 17 13 0.0 9 2 4.0
## 2 60003 Abu 26 13 18 22 3.0 5 8 6.0
## 3 60006 Samy 21 15 19 25 6.0 7 4 8.0
## 4 60008 Chong 25 10 17 14 2.0 3 4 5.0
## 5 60009 Paul 25 15 16 20 3.0 7 6 4.0
## 6 60011 John 18 15 19 22 4.0 7 4 7.0
## 7 60014 Devi 30 15 19 28 4.0 5 9 10.0
## 8 60015 Pillip 16 15 19 20 4.0 5 6 5.0
## 9 60023 Meilin 18 13 18 22 2.0 5 7 8.0
## 10 60025 Lily 30 14 18 24 5.5 6 5 7.5
## 11 60026 Jamil 12 10 12 12 1.0 5 1 6.0Using few available funcation to check the data frame
marks1 <- read.csv(file="marks1.csv", head=TRUE, sep=",")
columns_1 <- marks1[,c(1,3,5)]
columns_1## X test Prsnt
## 1 60001 15 17
## 2 60003 26 18
## 3 60006 21 19
## 4 60008 25 17
## 5 60009 25 16
## 6 60011 18 19
## 7 60014 30 19
## 8 60015 16 19
## 9 60023 18 18
## 10 60025 30 18
## 11 60026 12 12columns_2 <- marks1[,3:6]
columns_2## test asgn Prsnt Final
## 1 15 14 17 13
## 2 26 13 18 22
## 3 21 15 19 25
## 4 25 10 17 14
## 5 25 15 16 20
## 6 18 15 19 22
## 7 30 15 19 28
## 8 16 15 19 20
## 9 18 13 18 22
## 10 30 14 18 24
## 11 12 10 12 12marks3 <- marks1[marks1$test==25,]
marks3## X X.1 test asgn Prsnt Final q1 q2 q3 q4
## 4 60008 Chong 25 10 17 14 2 3 4 5
## 5 60009 Paul 25 15 16 20 3 7 6 4marks4 <- marks1[marks1$Final %in% c(22,20),]
marks4## X X.1 test asgn Prsnt Final q1 q2 q3 q4
## 2 60003 Abu 26 13 18 22 3 5 8 6
## 5 60009 Paul 25 15 16 20 3 7 6 4
## 6 60011 John 18 15 19 22 4 7 4 7
## 8 60015 Pillip 16 15 19 20 4 5 6 5
## 9 60023 Meilin 18 13 18 22 2 5 7 8marks5 <- marks1[with(marks1,test==25&Prsnt==17),]
marks5## X X.1 test asgn Prsnt Final q1 q2 q3 q4
## 4 60008 Chong 25 10 17 14 2 3 4 5Check the names of the variables in the data frame
names(marks1)## [1] "X" "X.1" "test" "asgn" "Prsnt" "Final" "q1" "q2" "q3"
## [10] "q4"Rename the first variable X to ID
colnames(marks1)[1] <- 'ID'
marks1## ID X.1 test asgn Prsnt Final q1 q2 q3 q4
## 1 60001 Ahmad 15 14 17 13 0.0 9 2 4.0
## 2 60003 Abu 26 13 18 22 3.0 5 8 6.0
## 3 60006 Samy 21 15 19 25 6.0 7 4 8.0
## 4 60008 Chong 25 10 17 14 2.0 3 4 5.0
## 5 60009 Paul 25 15 16 20 3.0 7 6 4.0
## 6 60011 John 18 15 19 22 4.0 7 4 7.0
## 7 60014 Devi 30 15 19 28 4.0 5 9 10.0
## 8 60015 Pillip 16 15 19 20 4.0 5 6 5.0
## 9 60023 Meilin 18 13 18 22 2.0 5 7 8.0
## 10 60025 Lily 30 14 18 24 5.5 6 5 7.5
## 11 60026 Jamil 12 10 12 12 1.0 5 1 6.0REname the second variable X.1 to StuName
colnames(marks1)[2] <- 'StuName'
marks1## ID StuName test asgn Prsnt Final q1 q2 q3 q4
## 1 60001 Ahmad 15 14 17 13 0.0 9 2 4.0
## 2 60003 Abu 26 13 18 22 3.0 5 8 6.0
## 3 60006 Samy 21 15 19 25 6.0 7 4 8.0
## 4 60008 Chong 25 10 17 14 2.0 3 4 5.0
## 5 60009 Paul 25 15 16 20 3.0 7 6 4.0
## 6 60011 John 18 15 19 22 4.0 7 4 7.0
## 7 60014 Devi 30 15 19 28 4.0 5 9 10.0
## 8 60015 Pillip 16 15 19 20 4.0 5 6 5.0
## 9 60023 Meilin 18 13 18 22 2.0 5 7 8.0
## 10 60025 Lily 30 14 18 24 5.5 6 5 7.5
## 11 60026 Jamil 12 10 12 12 1.0 5 1 6.0Remove the first two column from the data frame
new_marks1 <- marks1[,c(-1,-2)]
new_marks1## test asgn Prsnt Final q1 q2 q3 q4
## 1 15 14 17 13 0.0 9 2 4.0
## 2 26 13 18 22 3.0 5 8 6.0
## 3 21 15 19 25 6.0 7 4 8.0
## 4 25 10 17 14 2.0 3 4 5.0
## 5 25 15 16 20 3.0 7 6 4.0
## 6 18 15 19 22 4.0 7 4 7.0
## 7 30 15 19 28 4.0 5 9 10.0
## 8 16 15 19 20 4.0 5 6 5.0
## 9 18 13 18 22 2.0 5 7 8.0
## 10 30 14 18 24 5.5 6 5 7.5
## 11 12 10 12 12 1.0 5 1 6.0Use apply() function to sum all the marks in the data frame and put them in a new vector called Total and bind the vector to the data frame
Total <- apply(new_marks1,1,sum)
marks1 <- cbind(marks1,Total)
marks1## ID StuName test asgn Prsnt Final q1 q2 q3 q4 Total
## 1 60001 Ahmad 15 14 17 13 0.0 9 2 4.0 74
## 2 60003 Abu 26 13 18 22 3.0 5 8 6.0 101
## 3 60006 Samy 21 15 19 25 6.0 7 4 8.0 105
## 4 60008 Chong 25 10 17 14 2.0 3 4 5.0 80
## 5 60009 Paul 25 15 16 20 3.0 7 6 4.0 96
## 6 60011 John 18 15 19 22 4.0 7 4 7.0 96
## 7 60014 Devi 30 15 19 28 4.0 5 9 10.0 120
## 8 60015 Pillip 16 15 19 20 4.0 5 6 5.0 90
## 9 60023 Meilin 18 13 18 22 2.0 5 7 8.0 93
## 10 60025 Lily 30 14 18 24 5.5 6 5 7.5 110
## 11 60026 Jamil 12 10 12 12 1.0 5 1 6.0 59Using a user defined function called function(), use the apply() function to add variable 1 to variable 3, and write to a new variable in the data frame called CW
CW <- apply(new_marks1,1,function(x) {x[1]+ x[2]+ x[3]})
marks1 <- cbind(marks1,CW)
marks1## ID StuName test asgn Prsnt Final q1 q2 q3 q4 Total CW
## 1 60001 Ahmad 15 14 17 13 0.0 9 2 4.0 74 46
## 2 60003 Abu 26 13 18 22 3.0 5 8 6.0 101 57
## 3 60006 Samy 21 15 19 25 6.0 7 4 8.0 105 55
## 4 60008 Chong 25 10 17 14 2.0 3 4 5.0 80 52
## 5 60009 Paul 25 15 16 20 3.0 7 6 4.0 96 56
## 6 60011 John 18 15 19 22 4.0 7 4 7.0 96 52
## 7 60014 Devi 30 15 19 28 4.0 5 9 10.0 120 64
## 8 60015 Pillip 16 15 19 20 4.0 5 6 5.0 90 50
## 9 60023 Meilin 18 13 18 22 2.0 5 7 8.0 93 49
## 10 60025 Lily 30 14 18 24 5.5 6 5 7.5 110 62
## 11 60026 Jamil 12 10 12 12 1.0 5 1 6.0 59 34