Indexing in Matrices
Matrix elements are accessed with two indices: the row number and the column number. As usual, indexing starts at 1. Use square brackets [row, column] to specify the position of an element.
Single Elements
Provide both a row and a column index to extract a single value.
Example
1234567num <- 1:9 m <- matrix(num, nrow = 3, ncol = 3, byrow = T) # Element in row 2, column 2 (value 5) m[2, 2] # Element in row 1, column 3 (value 3) m[1, 3]
Multiple Elements
Use a vector of indices to extract multiple values at once.
Example
12345num <- 1:9 m <- matrix(num, nrow = 3, ncol = 3, byrow = T) # Elements in row 3, columns 2 and 3 m[3, c(2, 3)]
Entire Rows or Columns
Omit one of the indices to return a full row or column.
Example
1234567num <- 1:9 m <- matrix(num, nrow = 3, ncol = 3, byrow = T) # Entire first row m[1, ] # Entire third column m[, 3]
Swipe to start coding
You have a matrix named m:
2 4 6 8
10 12 14 16
Your tasks are to:
- Extract the element
12. - Extract the elements
4 6. - Extract the third column.
Solution
Thanks for your feedback!
single
Ask AI
Ask AI
Ask anything or try one of the suggested questions to begin our chat
Can you explain how to extract a submatrix from a matrix?
What happens if I use negative indices when accessing matrix elements?
How do I modify elements in a matrix using indexing?
Awesome!
Completion rate improved to 2.27Indexing in Matrices
Swipe to show menu
Matrix elements are accessed with two indices: the row number and the column number. As usual, indexing starts at 1. Use square brackets [row, column] to specify the position of an element.
Single Elements
Provide both a row and a column index to extract a single value.
Example
1234567num <- 1:9 m <- matrix(num, nrow = 3, ncol = 3, byrow = T) # Element in row 2, column 2 (value 5) m[2, 2] # Element in row 1, column 3 (value 3) m[1, 3]
Multiple Elements
Use a vector of indices to extract multiple values at once.
Example
12345num <- 1:9 m <- matrix(num, nrow = 3, ncol = 3, byrow = T) # Elements in row 3, columns 2 and 3 m[3, c(2, 3)]
Entire Rows or Columns
Omit one of the indices to return a full row or column.
Example
1234567num <- 1:9 m <- matrix(num, nrow = 3, ncol = 3, byrow = T) # Entire first row m[1, ] # Entire third column m[, 3]
Swipe to start coding
You have a matrix named m:
2 4 6 8
10 12 14 16
Your tasks are to:
- Extract the element
12. - Extract the elements
4 6. - Extract the third column.
Solution
Switch to desktop for real-world practiceContinue from where you are using one of the options belowThanks for your feedback!
single
