Type checking and conversion in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of type conversion with as.numeric()

What is the output of the following R code?

R Programming

x <- c("10", "20", "thirty", "40")
y <- as.numeric(x)
y

A [1] 10 20 NA 40

B [1] "10" "20" "thirty" "40"

C [1] 10 20 30 40

D [1] NA NA NA NA

💡 Hint

as.numeric() converts strings to numbers but returns NA for non-numeric strings.

The string "thirty" cannot be converted to a number, so as.numeric() returns NA for that element.

❓ Predict Output

intermediate

Result of is.integer() on numeric vector

What does the following R code print?

R Programming

v <- c(1, 2, 3)
is.integer(v)

A [1] TRUE

B [1] NA

C [1] FALSE

D Error: object 'v' not found

💡 Hint

In R, numeric vectors are by default of type double, not integer.

The vector v is numeric (double), so is.integer(v) returns FALSE.

❓ Predict Output

advanced

Behavior of as.character() on factor

What is the output of this R code?

R Programming

f <- factor(c("apple", "banana", "apple"))
char_vec <- as.character(f)
char_vec

A [1] "apple" "banana" "apple"

B [1] 1 2 1

C [1] "1" "2" "1"

D [1] NA NA NA

💡 Hint

as.character() converts factor levels back to their string values.

Factors store data as integers internally but as.character() returns the original strings.

❓ Predict Output

advanced

Output of typeof() on logical conversion

What is the output of this R code?

R Programming

x <- c(TRUE, FALSE, TRUE)
t <- as.integer(x)
t
typeof(t)

A

[1] 1 0 1
[1] "double"

B

[1] 1 0 1
[1] "integer"

C

[1] TRUE FALSE TRUE
[1] "logical"

D

[1] NA NA NA
[1] "integer"

💡 Hint

TRUE converts to 1 and FALSE to 0 when cast to integer.

as.integer converts logical TRUE/FALSE to 1/0 and typeof confirms the vector type is integer.

❓ Predict Output

expert

Result of coercion in mixed-type vector

What is the output of this R code?

R Programming

v <- c(1L, 2.5, TRUE, "4")
v
typeof(v)

A

[1] 1 2.5 1 NA
[1] "double"

B

[1] 1 2 1 4
[1] "integer"

C

[1] 1 2.5 1 4
[1] "double"

D

[1] "1" "2.5" "TRUE" "4"
[1] "character"

💡 Hint

When combining different types, R coerces all elements to the most flexible type.

Because of the character "4", all elements become character strings.