A Matrix is a collection of data values in 2 dimensions of the same basic data type, R creates a matrix of values using a ** matrix() **function.

It is similar to a vector and has one additional dimension attribute. We can check the R Matrices class using the * class()* function and ensure that the variable is a matrix or not.

## Creating a Matrix in R

See the basic syntax for creating a matrix in R using the * matrix()* function.

**matrix(vector,nrow,ncol,byrow)**

**vector**- a variable of vector datatype

**nrow**- the number of rows in a matrix

**ncol**- the number of column in a matrix

**byrow**- a boolean value, if it is true then input vector values will be arranged by row

See this example of creating a matrix

- #Create a matrix using Vector
- test_matrix<-matrix(c(1,2,3,4,5,6), nrow=2, ncol=2,byrow= TRUE)
- #Print matrix on console
- print(test_matrix)

and output is

- [,1] [,2]
- [1,] 1 2
- [2,] 3 4

## Accessing values of a Matrix

We can access an entire row, column or any specific value using row and column index of the matrix. See this example here to get an idea about it

- #Create a matrix using Vector
- test_matrix<-matrix(c(1,2,3,4,5,6), nrow=2, ncol=2,byrow= TRUE)
- #Print 1st row on console
- print(test_matrix[1,])
- #Print 2nd column on console
- print(test_matrix[,2])
- #Print 1st column of 2nd row on console
- print(test_matrix[2,1])

and output is like this

## Performing Arithmetic Operations on R Matrices

We can perform addition, subtraction, multiplication and division on the matrices that have the same dimension.

See this example.

- #Create two matrix using Vector
- first_matrix<-matrix(c(1,2,3,4,5,6), nrow=2, ncol=2,byrow= TRUE)
- sec_matrix<-matrix(c(7,8,9,10,11,12), nrow=2, ncol=2,byrow= TRUE)
- #First Matrix
- print(first_matrix)
- #Second Matrix
- print(sec_matrix)
- #Addition
- print(first_matrix + sec_matrix)
- #Subtraction
- print(first_matrix - sec_matrix)
- #Multiplication
- print(first_matrix * sec_matrix)
- #Division
- print(first_matrix / sec_matrix)

and see the output on the R console

## Add a new row or column in the existing Matrix

We can add a new row using * rbind()* and a column using

*function in an existing matrix.*

**cbind()**See this example

- #Create a matrix using Vector
- first_matrix<-matrix(c(1,2,3,4,5,6), nrow=2, ncol=2,byrow= TRUE)
- #First Matrix
- print(first_matrix)
- #Adding new row in matrix
- v <- c(89,90,91)
- first_matrix <- rbind(first_matrix,v)
- print(first_matrix)
- #Adding new column in matrix
- v <- c(92,93,94)
- first_matrix <- cbind(first_matrix,v)
- print(first_matrix)

and output is

## Combining Matrices in R

We can combine the column of two matrices that have the same number of rows using * cbind()* function.

- #Create two matrix using Vector
- first_matrix<-matrix(c(1,2,3,4,5,6), nrow=2, ncol=2,byrow= TRUE)
- sec_matrix<-matrix(c(7,8,9,10,11,12), nrow=2, ncol=2,byrow= TRUE)
- #First Matrix
- print(first_matrix)
- #Second Matrix
- print(sec_matrix)
- #Combining two matrices
- print(cbind(first_matrix,sec_matrix))

the output on R Console is

## Transpose Matrix

We can create the transpose matrix of a matrix using **t()** function.

- #Create a matrix using Vector
- first_matrix<-matrix(c(1,2,3,4,5,6), nrow=2, ncol=2,byrow= TRUE)
- #First Matrix
- print(first_matrix)
- #Transpose matrix
- print(t(first_matrix))

The output on R Console is

Cheers Happy Learning

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