Matrix dimensions in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a 3x3 matrix named mat filled with numbers 1 to 9.

R Programming

mat <- matrix(1:9, nrow = [1], ncol = 3)

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A1

B9

C3

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Setting nrow to 9 or 1, which creates wrong matrix dimensions.

The nrow argument sets the number of rows. To make a 3x3 matrix, nrow must be 3.

2fill in blank

medium

Complete the code to get the number of rows of matrix mat.

R Programming

num_rows <- nrow([1])

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Amatrix

Barray

Cdata

Dmat

Attempts:

3 left

💡 Hint

Common Mistakes

Using matrix or data which are not the matrix variable.

The function nrow() returns the number of rows of the matrix passed as argument. Here, the matrix is mat.

3fill in blank

hard

Fix the error in the code to get the number of columns of matrix mat.

R Programming

num_cols <- [1](mat)

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Ancol

Blength

Cnrow

Ddim

Attempts:

3 left

💡 Hint

Common Mistakes

Using nrow() which returns rows, not columns.

Using length() which returns total elements.

The function ncol() returns the number of columns of a matrix. Using nrow() or length() will not give the correct number of columns.

4fill in blank

hard

Fill both blanks to create a 2x4 matrix named m filled with numbers 1 to 8.

R Programming

m <- matrix(1:8, nrow = [1], ncol = [2])

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A2

B3

C4

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping rows and columns values.

Using wrong numbers like 3 or 5.

To create a 2x4 matrix, nrow must be 2 and ncol must be 4.

5fill in blank

hard

Fill all three blanks to create a matrix mat with 3 rows, 2 columns, and get its dimensions.

R Programming

mat <- matrix(1:6, nrow = [1], ncol = [2])
dims <- [3](mat)

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A2

Bdim

C3

Dncol

Attempts:

3 left

💡 Hint

Common Mistakes

Using ncol instead of dim to get dimensions.

Swapping rows and columns values.

Set nrow = 3 and ncol = 2 to create a 3x2 matrix. Use dim() to get both dimensions as a vector.