Why matrices handle tabular math in R Programming - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

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

R Programming

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

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

Ac(1, 2, 3)

B1:4

Cseq(1, 5)

Dc(1, 2)

Attempts:

3 left

💡 Hint

Common Mistakes

Using a vector with fewer or more elements than needed.

The matrix() function needs a vector of values. 1:4 creates numbers 1 to 4, perfect for a 2x2 matrix.

2fill in blank

medium

Complete the code to access the element in the first row and second column of the matrix.

R Programming

value <- mat[[1] , 2]

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A0

B2

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 as an index, which is invalid in R.

Matrix rows and columns start at 1 in R. To get the first row, use 1.

3fill in blank

hard

Fix the error in the code to multiply two matrices correctly.

R Programming

result <- mat1 [1] mat2

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A%*%

B*

C%

D%%

Attempts:

3 left

💡 Hint

Common Mistakes

Using * instead of %*% causes element-wise multiplication, not matrix multiplication.

Matrix multiplication in R uses the operator %*%. The * operator does element-wise multiplication.

4fill in blank

hard

Fill both blanks to create a matrix with 3 rows and 2 columns using numbers 1 to 6.

R Programming

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

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

A1:6

B3

C2

Dc(1, 2, 3)

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong number of values or wrong row count.

Use 1:6 for values and 3 for number of rows to get a 3x2 matrix.

5fill in blank

hard

Fill all three blanks to create a matrix from vector 'v', with 2 rows, 3 columns, and fill by row.

R Programming

mat <- matrix([1], nrow = [2], ncol = [3], byrow = TRUE)

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

Av

B2

C3

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing nrow and ncol values or forgetting to set byrow.

Use vector v, set rows to 2, columns to 3, and byrow = TRUE to fill matrix by rows.