Vector arithmetic (element-wise) in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is vector arithmetic (element-wise) in R?

It means performing operations like addition, subtraction, multiplication, or division on each pair of elements from two vectors of the same length, one by one.

intermediate

How does R handle vector addition when vectors have different lengths?

R recycles the shorter vector to match the length of the longer one, repeating its elements until lengths match, but it gives a warning if the longer vector's length is not a multiple of the shorter one.

beginner

What will be the result of c(1, 2, 3) + c(4, 5, 6) in R?

A new vector where each element is the sum of elements at the same position: c(5, 7, 9).

beginner

Explain element-wise multiplication of vectors in R with an example.

Element-wise multiplication multiplies each element of one vector by the corresponding element of another vector. For example, c(2, 3, 4) * c(5, 6, 7) results in c(10, 18, 28).

intermediate

What happens if you perform element-wise division with vectors of different lengths in R?

R recycles the shorter vector to match the longer one and divides elements pairwise, but warns if lengths are not multiples. For example, c(10, 20, 30, 40) / c(2, 5) results in c(5, 4, 15, 8).

What does element-wise addition of vectors mean in R?

A Adding the first element of one vector to all elements of the other

B Adding all elements of both vectors together

C Adding each element of one vector to the corresponding element of another vector

D Concatenating two vectors

Element-wise addition adds elements at the same positions in two vectors.

What will R do if you add vectors of different lengths?

A Ignore the shorter vector

B Return an error and stop

C Only add elements up to the length of the shorter vector

D Recycle the shorter vector to match the longer one

R recycles the shorter vector elements to match the longer vector length.

What is the result of c(3, 6, 9) * c(2, 4, 6) in R?

A c(6, 24, 54)

B c(1, 2, 3)

C c(5, 10, 15)

D c(3, 6, 9, 2, 4, 6)

Element-wise multiplication multiplies each pair: 3*2=6, 6*4=24, 9*6=54.

If you divide c(8, 16, 24) by c(2, 4), what will happen?

A Error due to different lengths

B Result c(4, 4, 12) with a warning

C Result c(4, 4, 6) with a warning

D Result c(4, 4, 12) without warning

Shorter vector c(2,4) is recycled to c(2,4,2). Division: 8/2=4, 16/4=4, 24/2=12 with a warning.

Which operator is used for element-wise subtraction in R?

A -

B +

C *

D /

The minus sign (-) subtracts elements pairwise in vectors.

Describe how R performs element-wise arithmetic operations on vectors and what happens when vectors have different lengths.

Think about how R matches elements by position and repeats shorter vectors.

Give examples of element-wise addition, multiplication, and division of vectors in R, explaining the results.

Use simple vectors like c(1,2,3) and c(4,5,6) to illustrate.