Get element at the specific position from matrix in R

At any point in time, a matrix may be required to be traversed for an element at a specific position. In this article, we are going to access the elements from a matrix in R Programming Language using integer vector, and logical vector as the index.

Accessing Elements in a Matrix

In R Programming Language we have several methods to Accessing Elements in a Matrix In R we can access matrix elements using square brackets [ ] notation.

Create a matrix

R

# Create a matrix
mat <- matrix(1:12,3,4)

mat

Output:

     [,1] [,2] [,3] [,4]
[1,]    1    4    7   10
[2,]    2    5    8   11
[3,]    3    6    9   12

Accessing Single Element in a Matrix

R

# Create a matrix
mat <- matrix(1:12,3,4)
mat

# Access the element in the 1st row and 2nd column
element <- mat[1, 2]
print(element)

Output:

     [,1] [,2] [,3] [,4]
[1,]    1    4    7   10
[2,]    2    5    8   11
[3,]    3    6    9   12

[1] 4

Accessing Entire Row or Column

R

# Access the entire 2nd row
row_vector <- mat[2, ]
print(row_vector)

# Access the entire 3rd column
col_vector <- mat[, 3]
print(col_vector)

Output:

[1]  2  5  8 11

[1] 7 8 9

Accessing Subsetting Matrix

R

# Create a 3x4 matrix
mat <- matrix(1:12,3,4)

# Subset a 2x2 matrix from the original
subset_mat <- mat[1:2, 2:3]
print(subset_mat)

Output:

     [,1] [,2]
[1,]    4    7
[2,]    5    8

Accessing matrix Conditional Access

R

# Create a 3x4 matrix
mat <- matrix(1:12,3,4)

# Access elements greater than 5
greater_than_5 <- mat[mat > 5]
print(greater_than_5)

Output:

[1]  6  7  8  9 10 11 12

These methods provide flexibility depending on our specific needs and the structure of our matrices. Choose the one that best fits our use case.