Matrix arithmetic in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a 2x2 matrix with values 1 to 4.

R Programming

mat <- matrix(1:4, nrow = [1], ncol = 2)

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

A1

B3

C2

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong number of rows like 3 or 4.

Confusing rows and columns.

The matrix has 2 rows and 2 columns, so nrow = 2 is correct.

2fill in blank

medium

Complete the code to add two matrices A and B.

R Programming

result <- [1] + B

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AA

BB

Cmatrix

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Using sum which sums all elements instead of element-wise addition.

Using matrix keyword incorrectly.

To add two matrices, use the + operator between them. Here, A + B.

3fill in blank

hard

Fix the error in the code to multiply matrices X and Y.

R Programming

product <- X [1] Y

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A*

B%*%

C%

D%%

Attempts:

3 left

💡 Hint

Common Mistakes

Using * which does element-wise multiplication.

Using modulo operators like %% or %.

Matrix multiplication in R uses the operator %*%, not *.

4fill in blank

hard

Fill both blanks to create a matrix M with 3 rows and 4 columns filled by row.

R Programming

M <- matrix(1:12, nrow = [1], ncol = [2], byrow = TRUE)

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A3

B4

CFALSE

DTRUE

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping rows and columns.

Setting byrow to FALSE by mistake.

The matrix has 3 rows and 4 columns, so nrow = 3 and ncol = 4.

5fill in blank

hard

Fill all three blanks to create a named matrix mat with row and column names.

R Programming

mat <- matrix(1:6, nrow = [1], ncol = [2], dimnames = list([3], c("A", "B")))

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

A2

B3

Cc("Row1", "Row2", "Row3")

Dc("Row1", "Row2")

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching row names length with number of rows.

Swapping rows and columns counts.

The matrix has 3 rows and 2 columns, so nrow = 3 and ncol = 2. The row names vector must match the number of rows, so c("Row1", "Row2", "Row3") is correct.