Numeric and character vectors in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a numeric vector with values 1, 2, and 3.

R Programming

vec <- c([1])

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

A1, 2, 3

B"1", "2", "3"

Cc(1, 2, 3)

D1:3

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around numbers creates character vectors instead of numeric.

Using c(1:3) inside c() is redundant.

The c() function combines values into a vector. Here, 1, 2, 3 creates a numeric vector.

2fill in blank

medium

Complete the code to create a character vector with the names "apple", "banana", and "cherry".

R Programming

fruits <- c([1])

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

Ac("apple", "banana", "cherry")

Bapple, banana, cherry

C"apple", "banana", "cherry"

D'apple', 'banana', 'cherry'

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes makes R think these are variable names, causing errors.

Using single quotes is allowed but less common in R.

Character values must be in quotes inside the c() function. Double quotes are standard in R.

3fill in blank

hard

Fix the error in the code to create a numeric vector from 5 to 10.

R Programming

numbers <- [1](5, 10)

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

Ac

Brange

Cvector

Dseq

Attempts:

3 left

💡 Hint

Common Mistakes

Using c(5, 10) creates a vector with only two numbers, not a sequence.

Using vector() creates an empty vector, not a sequence.

The seq() function generates sequences from a start to an end number. c(5, 10) just combines two numbers.

4fill in blank

hard

Fill both blanks to create a character vector of three fruits and check its type.

R Programming

fruits <- c([1])
is_char <- is.[2](fruits)

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

A"orange", "pear", "grape"

Bnumeric

Ccharacter

D"apple", "banana", "cherry"

Attempts:

3 left

💡 Hint

Common Mistakes

Using numeric type check on character vectors causes FALSE result.

Not quoting fruit names causes errors.

The vector must contain character strings in quotes. The function is.character() checks if the vector is character type.

5fill in blank

hard

Fill all three blanks to create a numeric vector, get its length, and access the second element.

R Programming

nums <- c([1])
len <- length([2])
second <- [3][2]

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

A10, 20, 30

Bnums

Dc(10, 20, 30)

Attempts:

3 left

💡 Hint

Common Mistakes

Putting c(10, 20, 30) inside c() causes nested vectors.

Using wrong variable names causes errors.

Use c(10, 20, 30) to create the vector, but since the blank is inside c(), only the numbers go in the first blank. The variable nums is used to get length and access elements.

Practice

1. Which of the following correctly creates a numeric vector in R?

easy

A. c(TRUE, FALSE, TRUE)

B. c("one", "two", "three")

C. c(1, "two", 3)

D. c(1, 2, 3, 4)

Solution

1. Step 1: Understand numeric vector creation

   Numeric vectors contain only numbers, so elements must be numeric values.

2. Step 2: Check each option's elements

   c(1, 2, 3, 4) has only numbers, so it is a numeric vector. c("one", "two", "three") has text, c(TRUE, FALSE, TRUE) has logical values, and c(1, "two", 3) mixes numbers and text, which converts all to characters.

3. Final Answer:

   c(1, 2, 3, 4) -> Option D

4. Quick Check:

   Numeric vector = c(1, 2, 3, 4) [OK]

Hint: Numeric vectors contain only numbers inside c() [OK]

Common Mistakes:

• Mixing numbers and text creates character vector
• Confusing logical vectors with numeric
• Using quotes around numbers

2. Which of these is the correct syntax to create a character vector in R?

easy

A. c(1, 2, 3)

B. c("apple", "banana", "cherry")

C. c(TRUE, FALSE, TRUE)

D. c(1, "banana", 3)

Solution

1. Step 1: Identify character vector syntax

   Character vectors contain text strings, which must be inside quotes.

2. Step 2: Check options for quoted text

   c("apple", "banana", "cherry") has all elements as quoted text strings, so it is a character vector. c(1, 2, 3) is numeric, c(TRUE, FALSE, TRUE) is logical, and c(1, "banana", 3) mixes types causing coercion.

3. Final Answer:

   c("apple", "banana", "cherry") -> Option B

4. Quick Check:

   Character vector = c("apple", "banana", "cherry") [OK]

Hint: Use quotes around text to create character vectors [OK]

Common Mistakes:

• Forgetting quotes around text
• Mixing types in one vector
• Using numbers without quotes for text

3. What is the output of this R code?

x <- c(5, 10, 15)
y <- c("a", "b", "c")
z <- c(x, y)
print(z)

medium

A. [1] "5" "10" "15" "a" "b" "c"

B. [1] 5 10 15 "a" "b" "c"

C. [1] 5 10 15 NA NA NA

D. Error: cannot combine numeric and character vectors

Solution

1. Step 1: Understand vector combining rules in R

   When combining numeric and character vectors, R converts all elements to character to keep the same type.

2. Step 2: Analyze the combined vector z

   Vector z contains numbers 5, 10, 15 and characters "a", "b", "c". All numbers become strings, so print shows all as character strings.

3. Final Answer:

   [1] "5" "10" "15" "a" "b" "c" -> Option A

4. Quick Check:

   Mixed vector coerces to character = [1] "5" "10" "15" "a" "b" "c" [OK]

Hint: Mixed types in vector become character strings [OK]

Common Mistakes:

• Expecting numeric values to stay numeric
• Thinking R throws error on combining types
• Assuming NA values appear for mismatched types

4. Identify the error in this R code:

vec <- c(1, 2, "three", 4)
sum(vec)

medium

A. No error; sum returns 10

B. sum() returns NA due to mixed types

C. Error because sum() cannot handle character vectors

D. Error because c() cannot mix numbers and text

Solution

1. Step 1: Understand vector creation with mixed types

   c(1, 2, "three", 4) creates a character vector because of the text element "three".

2. Step 2: Check sum() behavior on character vectors

   sum() expects numeric input. Passing a character vector causes an error because it cannot sum text.

3. Final Answer:

   Error because sum() cannot handle character vectors -> Option C

4. Quick Check:

   sum(character vector) = Error [OK]

Hint: sum() needs numeric vectors, not characters [OK]

Common Mistakes:

• Assuming sum() converts characters to numbers
• Thinking c() forbids mixing types (it coerces instead)
• Expecting sum() to return NA silently

5. You have two vectors:

nums <- c(2, 4, 6, 8)
chars <- c("2", "4", "6", "8")

How can you create a numeric vector from chars and add it to nums element-wise?

hard

A. nums + as.numeric(chars)

B. nums + chars

C. as.character(nums) + chars

D. sum(nums, chars)

Solution

1. Step 1: Convert character vector to numeric

   Use as.numeric(chars) to change text numbers to numeric values.

2. Step 2: Add numeric vectors element-wise

   Adding nums + as.numeric(chars) adds corresponding elements correctly.

3. Final Answer:

   nums + as.numeric(chars) -> Option A

4. Quick Check:

   Convert chars to numeric before adding = nums + as.numeric(chars) [OK]

Hint: Convert text to numbers with as.numeric() before math [OK]

Common Mistakes:

• Adding numeric and character vectors directly
• Using sum() instead of element-wise addition
• Converting numeric to character instead of chars to numeric