Comparison operators in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of vector comparison with recycling

What is the output of this R code?

c(1, 2, 3, 4) > c(2, 2)

R Programming

c(1, 2, 3, 4) > c(2, 2)

A [1] TRUE TRUE TRUE TRUE

B [1] TRUE FALSE TRUE FALSE

C [1] FALSE FALSE TRUE TRUE

D [1] FALSE TRUE TRUE TRUE

💡 Hint

Remember that R recycles shorter vectors to match the length of longer vectors.

The shorter vector c(2, 2) is recycled to c(2, 2, 2, 2). Then element-wise comparison is done: 1>2 is FALSE, 2>2 is FALSE, 3>2 is TRUE, 4>2 is TRUE.

❓ Predict Output

intermediate

Output of chained comparison operators

What is the output of this R code?

5 > 3 & 2 < 4

R Programming

5 > 3 & 2 < 4

A [1] TRUE

B [1] FALSE

C [1] TRUE TRUE

D [1] FALSE FALSE

💡 Hint

The & operator checks if both conditions are TRUE.

5 > 3 is TRUE and 2 < 4 is TRUE, so TRUE & TRUE returns TRUE.

❓ Predict Output

advanced

Output of comparison with NA values

What is the output of this R code?

c(1, NA, 3) == 3

R Programming

c(1, NA, 3) == 3

A [1] FALSE NA TRUE

B [1] FALSE FALSE TRUE

C [1] TRUE NA TRUE

D [1] NA NA TRUE

💡 Hint

Comparisons with NA produce NA unless the value is known to be equal or not.

1 == 3 is FALSE, NA == 3 is NA (unknown), 3 == 3 is TRUE.

❓ Predict Output

advanced

Output of comparing factors with different levels

What is the output of this R code?

f1 <- factor(c("a", "b"))
f2 <- factor(c("b", "a"))
f1 == f2

R Programming

f1 <- factor(c("a", "b"))
f2 <- factor(c("b", "a"))
f1 == f2

A [1] FALSE TRUE

B [1] TRUE TRUE

C [1] TRUE FALSE

D [1] FALSE FALSE

💡 Hint

Factors compare underlying integer codes, not just labels.

f1 has levels a=1, b=2 so codes 1,2. f2 has levels b=1, a=2 so first element 'b' (code 1), second 'a' (code 2), codes 1,2. Thus 1==1 TRUE, 2==2 TRUE.

🧠 Conceptual

expert

Behavior of comparison operators with matrices

Given two matrices:

m1 <- matrix(1:4, nrow=2)
m2 <- matrix(c(2, 2, 3, 3), nrow=2)

What is the output of m1 >= m2?

R Programming

m1 <- matrix(1:4, nrow=2)
m2 <- matrix(c(2, 2, 3, 3), nrow=2)
m1 >= m2

A

     [,1]  [,2]
[1,] FALSE FALSE
[2,]  TRUE  TRUE

B

     [,1]  [,2]
[1,] FALSE  TRUE
[2,]  TRUE  TRUE

C

     [,1]  [,2]
[1,]  TRUE FALSE
[2,] FALSE  TRUE

D

     [,1]  [,2]
[1,]  TRUE  TRUE
[2,] FALSE FALSE

💡 Hint

Comparison is element-wise between corresponding elements of matrices.

m1 is matrix: [,1] [,2] [1,] 1 3 [2,] 2 4 m2 is matrix: [,1] [,2] [1,] 2 3 [2,] 2 3 Comparisons: 1 >= 2 is FALSE 3 >= 3 is TRUE 2 >= 2 is TRUE 4 >= 3 is TRUE So output matrix is: [,1] [,2] [1,] FALSE TRUE [2,] TRUE TRUE