S4 object system in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a new S4 class named "Person".

R Programming

setClass("Person", slots = list(name = "character", age = [1]))

Drag options to blanks, or click blank then click option'

Anumeric

Blogical

Cinteger

Ddata.frame

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'numeric' instead of 'integer' for age slot.

Using 'logical' which is for TRUE/FALSE values.

The age slot should be of type integer to store whole numbers representing age.

2fill in blank

medium

Complete the code to create a new object of class "Person" with name "Alice" and age 30.

R Programming

alice <- new("Person", name = "Alice", age = [1])

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A"30"

B30L

C30.0

Das.character(30)

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string "30" instead of an integer.

Using a numeric 30.0 which is double, not integer.

The age slot expects an integer, so use 30L to specify an integer literal in R.

3fill in blank

hard

Fix the error in the method definition for the "show" function for class "Person".

R Programming

setMethod("show", "Person", function(object) {
  cat("Name:", object@name, "\n")
  cat("Age:", object@[1], "\n")
})

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AAge

Bages

CAGE

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using capitalized or plural forms of the slot name.

Using a non-existent slot name.

The slot name is case-sensitive and defined as age, so use object@age to access it.

4fill in blank

hard

Fill both blanks to define a method "birthday" that increases the age by 1 for a "Person" object.

R Programming

setGeneric("birthday", function(object) standardGeneric("birthday"))

setMethod("birthday", "Person", function(object) {
  object@[1] <- object@[2] + 1
  return(object)
})

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Aage

Bname

Attempts:

3 left

💡 Hint

Common Mistakes

Using different slot names for assignment and addition.

Trying to update the name slot instead of age.

The method should update the age slot by adding 1 to the current age.

5fill in blank

hard

Fill all three blanks to create a valid S4 class "Employee" that extends "Person" and adds a slot "salary" of type numeric.

R Programming

setClass("Employee",
  slots = list([1] = [2]),
  contains = [3]
)

Drag options to blanks, or click blank then click option'

Asalary

Bnumeric

C"Person"

Dcharacter

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong slot names or types.

Not quoting the class name in 'contains'.

The Employee class adds a salary slot of type numeric and extends the Person class.