Convert an Object into a Matrix in R Programming - as.matrix() Function

The as.matrix() function within R converts objects of various classes into a matrix. This can be helpful to work with structures of various data that can be converted into the matrix structure so that it becomes easier to analyze.

Syntax:

as.matrix(x)

Parameters: 

• x: Object to be converted

Example 1: Convert vector to the matrix using as.matrix()

# Creating a vector
x <- c(1:9)

# Calling as.matrix() Function
as.matrix(x)

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

Example 2: Convert a Data Frame to a Matrix

# Calling pre-defined data set
BOD

# Calling as.matrix() Function
as.matrix(BOD)

  Time demand
1    1    8.3
2    2   10.3
3    3   19.0
4    4   16.0
5    5   15.6
6    7   19.8
     Time demand
[1,]    1    8.3
[2,]    2   10.3
[3,]    3   19.0
[4,]    4   16.0
[5,]    5   15.6
...

Example 3: Convert a Sparse Matrix to a Dense Matrix

library(Matrix)

# Create a sparse matrix
s_mat <- Matrix(c(0, 0, 0, 0, 0, 0, 1, 2, 0), nrow = 3, ncol = 3)
s_mat

# Convert to a dense matrix
d_mat <- as.matrix(s_mat)
d_mat

Output

3 x 3 sparse Matrix of class "dtCMatrix"

[1,] . . 1
[2,] . . 2
[3,] . . .
[,1] [,2] [,3]
[1,] 0 0 1
[2,] 0 0 2
[3,] 0 0 0

Example 4: Convert a SpatialPointsDataFrame to a Matrix

library(sp)

# Create a SpatialPointsDataFrame
co <- cbind(c(1, 2, 3), c(4, 5, 6))

sdf <- SpatialPointsDataFrame(coords = co, data = data.frame(ID = 1:3))
sdf
# Convert to a matrix of coordinates
c_mat <- as.matrix(co)
c_mat

Output

coordinates ID
1 (1, 4) 1
2 (2, 5) 2
3 (3, 6) 3
[,1] [,2]
[1,] 1 4
[2,] 2 5
[3,] 3 6