Vector creation with c() in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of combining different types with c()

What is the output of this R code?

x <- c(1, TRUE, "3", 4.5)
print(x)

R Programming

x <- c(1, TRUE, "3", 4.5)
print(x)

A [1] 1 1 3 4.5

B [1] "1" "TRUE" "3" "4.5"

C [1] "1" "1" "3" "4.5"

D [1] 1 TRUE "3" 4.5

💡 Hint

Remember that c() converts all elements to the most flexible type to keep them in one vector.

In R, when combining different types with c(), all elements are coerced to a common type. Here, numeric and logical values are converted to character because of the presence of a character "3". TRUE becomes "TRUE" as character.

❓ Predict Output

intermediate

Length of vector created with c()

What is the length of the vector created by this code?

v <- c(NA, NULL, 5, c(2, 3))
length(v)

R Programming

v <- c(NA, NULL, 5, c(2, 3))
length(v)

A 5

B 2

C 3

D 4

💡 Hint

Remember that NULL is ignored inside c(), but NA counts as an element.

NULL is dropped when combined with c(), so the vector is c(NA, 5, 2, 3) which has length 4.

🔧 Debug

advanced

Why does this c() call produce an error?

This code produces an error. What is the cause?

v <- c(1, 2, 3, , 5)

R Programming

v <- c(1, 2, 3, , 5)

A Syntax error due to missing value between commas

B No error, code runs fine

C Runtime error because c() cannot handle more than 4 elements

D Type error because 5 is not compatible with previous numbers

💡 Hint

Check the commas carefully inside the c() function.

There is a missing value between two commas, which is a syntax error in R.

🧠 Conceptual

advanced

Behavior of c() with named elements

What is the output of this R code?

v <- c(a=1, b=2, 3)
names(v)

R Programming

v <- c(a=1, b=2, 3)
names(v)

A [1] "a" "b" "3"

B [1] "a" "b" "c"

C [1] "a" "b" ""

D [1] NULL

💡 Hint

Only elements explicitly named get names; unnamed elements have empty names.

The first two elements have names "a" and "b". The third element is unnamed, so its name is an empty string "".

❓ Predict Output

expert

Output of nested c() calls with mixed types

What is the output of this R code?

v <- c(1, c(TRUE, "text"), 3.5)
print(v)

R Programming

v <- c(1, c(TRUE, "text"), 3.5)
print(v)

A [1] "1" "TRUE" "text" "3.5"

B [1] 1 1 "text" 3.5

C [1] "1" "1" "text" "3.5"

D [1] 1 TRUE "text" 3.5

💡 Hint

Remember that c() flattens nested vectors and coerces types to the most flexible one.

The inner c(TRUE, "text") coerces TRUE to character "TRUE". Then the outer c() flattens and coerces all to character because of "text". 1 becomes "1", 3.5 becomes "3.5", "TRUE" and "text" remain.