Exercise 1:
Create a data frame named students with the following columns: Name, Age, Grade, and Subject. Populate it with at least 5 rows of sample data.
students<- data.frame(
name = c('Ali', "Bob", "Lukman", "Aishah", "Kamal"),
age = c(10, 20, 19, 28, 31),
grade = as.factor(c("A", "A", "B", "B", "C")),
subject = as.factor(c("English", "History", "Math", "Economy", "Geometry"))
)
students name age grade subject
1 Ali 10 A English
2 Bob 20 A History
3 Lukman 19 B Math
4 Aishah 28 B Economy
5 Kamal 31 C GeometryDisplay the structure of the students data frame using the str() function.
str(students)'data.frame': 5 obs. of 4 variables:
$ name : chr "Ali" "Bob" "Lukman" "Aishah" ...
$ age : num 10 20 19 28 31
$ grade : Factor w/ 3 levels "A","B","C": 1 1 2 2 3
$ subject: Factor w/ 5 levels "Economy","English",..: 2 4 5 1 3Add a new column to the students data frame named Attendance and populate it with sample data
students$Attendance<- as.factor(c("Present", "Present", "Absent", "Absent", "Present"))
students$Attendance[1] Present Present Absent Absent Present
Levels: Absent PresentExercise 2:
From the mtcars dataset, extract the mpg (miles per gallon) and hp (horsepower) columns and save them as a new data frame named car_specs.
car_specs<-mtcars[ , c("mpg","hp")]Retrieve the first 6 rows of the car_specs data frame.
head(car_specs) mpg hp
Mazda RX4 21.0 110
Mazda RX4 Wag 21.0 110
Datsun 710 22.8 93
Hornet 4 Drive 21.4 110
Hornet Sportabout 18.7 175
Valiant 18.1 105Create a subset of mtcars containing only cars with 6 cylinders (cyl).
mtcars[mtcars$cyl==6, ] mpg cyl disp hp drat wt qsec vs am gear carb
Mazda RX4 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4
Mazda RX4 Wag 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4
Hornet 4 Drive 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1
Valiant 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1
Merc 280 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4
Merc 280C 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4
Ferrari Dino 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6Exercise 3:
Calculate the median horsepower (hp) of all cars in the mtcars dataset.
median(mtcars$hp)[1] 123How many cars in the dataset have an automatic transmission (am column: 0 represents automatic, 1 represents manual)?
length(mtcars[mtcars$am==0, ])[1] 11Which car model in the mtcars dataset has the highest miles per gallon (mpg)?
rownames(mtcars)[which.max(mtcars$mpg)][1] "Toyota Corolla"Exercise 4:
Extract and display all cars from mtcars with 4 cylinders (cyl).
rownames(mtcars[mtcars$cyl == 4, ]) [1] "Datsun 710" "Merc 240D" "Merc 230" "Fiat 128"
[5] "Honda Civic" "Toyota Corolla" "Toyota Corona" "Fiat X1-9"
[9] "Porsche 914-2" "Lotus Europa" "Volvo 142E" How many cars in the mtcars dataset have more than 100 horsepower (hp) and weigh (column wt) less than 3,000 lbs?
nrow(mtcars[mtcars$hp > 100 & mtcars$wt < 3, ])[1] 5Retrieve all car models from mtcars that have an automatic transmission and can cover more than 20 miles per gallon.
rownames(mtcars[mtcars$am == 0 & mtcars$mpg > 20, ])[1] "Hornet 4 Drive" "Merc 240D" "Merc 230" "Toyota Corona" Exercise 5:
How many rows and columns are present in the mtcars dataset?
dim(mtcars)[1] 32 11What are the names of all the columns in the dataset?
colnames(mtcars) [1] "mpg" "cyl" "disp" "hp" "drat" "wt" "qsec" "vs" "am" "gear"
[11] "carb"Display the last 8 rows of the dataset.
tail(mtcars, 8) mpg cyl disp hp drat wt qsec vs am gear carb
Pontiac Firebird 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2
Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1
Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
Ford Pantera L 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4
Ferrari Dino 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6
Maserati Bora 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8
Volvo 142E 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2Exercise 6:
Calculate the median horsepower (hp) of all cars in the dataset.
median(mtcars$hp)[1] 123How many cars in the dataset have an automatic transmission (am column: 0 represents automatic, 1 represents manual)?
sum(mtcars$am == 0)[1] 19Which car model has the highest miles per gallon (mpg)?
rownames(mtcars)[which.max(mtcars$mpg)][1] "Toyota Corolla"Exercise 7:
Extract and display all cars with 4 cylinders (cyl).
rownames(mtcars[mtcars$cyl == 4, ]) [1] "Datsun 710" "Merc 240D" "Merc 230" "Fiat 128"
[5] "Honda Civic" "Toyota Corolla" "Toyota Corona" "Fiat X1-9"
[9] "Porsche 914-2" "Lotus Europa" "Volvo 142E" How many cars have more than 100 horsepower (hp) and weigh (column wt) less than 3,000 lbs?
nrow(mtcars[mtcars$hp > 100 & mtcars$wt < 3, ])[1] 5Retrieve all car models that have an automatic transmission and can cover more than 20 miles per gallon.
rownames(mtcars[mtcars$am == 0 & mtcars$mpg > 20, ])[1] "Hornet 4 Drive" "Merc 240D" "Merc 230" "Toyota Corona" GRADE ASSIGNMENT
score <- 87
if (score >= 90) {
print(“A”)
} else if (score >= 80) {
print(“B”)
} else if (score >= 70) {
print(“C”)
} else if (score >= 60) {
print(“D”)
} else {
print(“FAIL”)
}
GIVEN SCORE == 87 CLASSIFY SCORE, >=90 A, >=80 - 90 AS B, MPORE THAN 70-80 AS C, 60 - 70 AS D AND ELSE IF FAIL
score <- 87
if (score >= 90) {
print("A")
} else if (score >= 80) {
print("B")
} else if (score >= 70) {
print("C")
} else if (score >= 60) {
print("D")
} else {
print("FAIL")
}[1] "B"