How to Create a Matrix in R - Step by Step Examples

How to Create a Matrix in R ?

Answer

To create matrices in R, you can use the matrix() function. This function allows you to create a matrix by specifying the data, the number of rows, and the number of columns.

✐ Examples

1 Creating a 2x3 Matrix

In this example,

We start by creating a vector named data with the values 1:6, which generates a sequence of numbers from 1 to 6.
Next, we use the matrix() function to create a matrix named mat. The first argument to matrix() is the data vector we just created.
We then specify the number of rows in the matrix using the nrow argument, setting it to 2. This means our matrix will have 2 rows.
We also specify the number of columns using the ncol argument, setting it to 3. This means our matrix will have 3 columns.
The matrix() function arranges the data in a column-major order by default, filling the matrix by columns. So, the resulting matrix mat will look like this:
```
1 3 5
2 4 6
```
Finally, we use the print() function to display the matrix mat.

R Program

data <- 1:6
mat <- matrix(data, nrow = 2, ncol = 3)
print(mat)

Output

     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6

2 Creating a 3x3 Matrix with Row-wise Filling

In this example,

We start by creating a vector named data with the values 1:9, which generates a sequence of numbers from 1 to 9.
Next, we use the matrix() function to create a matrix named mat. The first argument to matrix() is the data vector we just created.
We then specify the number of rows in the matrix using the nrow argument, setting it to 3. This means our matrix will have 3 rows.
We also specify the number of columns using the ncol argument, setting it to 3. This means our matrix will have 3 columns.
We use the byrow argument and set it to TRUE to fill the matrix by rows instead of the default column-major order. So, the resulting matrix mat will look like this:
```
1 2 3
4 5 6
7 8 9
```
Finally, we use the print() function to display the matrix mat.

R Program

data <- 1:9
mat <- matrix(data, nrow = 3, ncol = 3, byrow = TRUE)
print(mat)

Output

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

3 Creating a 4x2 Matrix and Naming Rows and Columns

In this example,

We start by creating a vector named data with the values 1:8, which generates a sequence of numbers from 1 to 8.
Next, we use the matrix() function to create a matrix named mat. The first argument to matrix() is the data vector we just created.
We then specify the number of rows in the matrix using the nrow argument, setting it to 4. This means our matrix will have 4 rows.
We also specify the number of columns using the ncol argument, setting it to 2. This means our matrix will have 2 columns.
The matrix() function arranges the data in a column-major order by default, filling the matrix by columns. So, the resulting matrix mat will look like this:
```
1 5
2 6
3 7
4 8
```
We then use the rownames() function to assign names to the rows of the matrix, setting them to c("Row1", "Row2", "Row3", "Row4").
We also use the colnames() function to assign names to the columns of the matrix, setting them to c("Col1", "Col2").
Finally, we use the print() function to display the matrix mat with its row and column names.

R Program

data <- 1:8
mat <- matrix(data, nrow = 4, ncol = 2)
rownames(mat) <- c("Row1", "Row2", "Row3", "Row4")
colnames(mat) <- c("Col1", "Col2")
print(mat)

Output

     Col1 Col2
Row1    1    5
Row2    2    6
Row3    3    7
Row4    4    8

Summary

In this tutorial, we learned How to Create a Matrix in R language with well detailed examples.

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How to Create a Matrix in R - Step by Step Examples

How to Create a Matrix in R ?

Answer

✐ Examples

1 Creating a 2x3 Matrix

R Program

Output

2 Creating a 3x3 Matrix with Row-wise Filling

R Program

Output

3 Creating a 4x2 Matrix and Naming Rows and Columns

R Program

Output

Summary

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