An Array in R Programming is simply called as the multi-dimensional Data structure. In R Array, data is stored in matrices, row and columns, and we can access the matrix element using the matrix level, row index and column index. In this article we will show you, How to Create an array, How to Access the Array Elements, Performing Arithmetic Operations on Arrays with example

## R Array Syntax

The basic syntax of the Array in R Programming language is as shown below:

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Array_Name <- array(data, dim = (row_Size, column_Size, matrices, dimnames) |

If you observe the above code snippet, data is a Vector and

**Matrices:**It will decide the number of Matrices an array can accept. Array in R is always a Multi Dimensional, it means more than 1 matrix with rows and columns.**Row_Size:**Please specify the number of Row elements an array can store. For example, Row_Size =5 then each matrix in an array will have 5 rows.**Column_Size:**Number of Column elements an array can store. For example, Column_Size = 6 then each matrix in an array will have 6 Columns.**dimnames:**It is used to change the default Row, Column, Matrices names to more meaningful names.

## Create an Array in R

In this example, we will create an Array. Following code snippet will show you the most traditional way to create an Array in R Programming language.

**R CODE**

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# Create Array in R A <- array(1: 24, dim = c(3, 4, 2)) print(A) vect1 <- c(10, 20, 30, 40) vect2 <- c(50, 60, 70, 80, 90, 100) B <- array(c(vect1, vect2), dim = c(3, 3, 2)) print(B) |

**OUTPUT**

**ANALYSIS**

Below statement will create an Array of elements from 1 to 24 arranged in two matrices and each matrices contains three rows and four columns.

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A <- array(1: 24, dim = c(3, 4, 2)) |

Next, we created two vectors

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vect1 <- c(10, 20, 30, 40) vect2 <- c(50, 60, 70, 80, 90, 100) |

From the above screenshot you can observe that, we are using c or concatenation function to combine those vectors to create an array of the elements are arranged in two matrices. Each matrix will contain three rows and three columns.

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B <- array(c(vect1, vect2), dim = c(3, 3, 2)) |

### Defining Row names and Column names for Array in R

In this example we will show you, How to replace the default names of the Rows, Columns, and Matrix or define new names to the Rows, Columns, and Matrices in Arrays. We can achieve the same using *dimnames* as: *x <- matrix(1:12, dimnames = list(rowNames, columnNames, matrixNames) *

**R CODE**

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# Create Array in R A <- array(1: 24, dim = c(3, 4, 2)) print(A) # Defining Row names and Column names of Matrix in R row.names <- c("Row1", "Row2", "Row3") column.names <-c("Col1", "Col2", "Col3", "Col4") matrix.names <-c("Matrixl1", "Matrix2") B <- array(1: 24, dim = c(3, 4, 2), dimnames = list(row.names, column.names, matrix.names)) print(B) |

**OUTPUT**

## Accessing R Array Elements

In R programming, We can use the index position to access the array elements. Using index we can access or alter/change each and every individual element present in an array. Index value starts at 1 and end at n where n is the size of a matrix, row or column. The syntax behind this is Array accessing is: Array_Name[row_position, Column_Position, Matrix_Level]. For example, we declared an array of two matrices of size 6 rows * 4 columns. To access or alter 1^{st} value use Array_name[1, 1, 1], to access or alter 2^{nd} row 3^{rd} column value at 1^{st }Matrix level then use Array_name[2, 3, 1] and to access the 6^{th} row 4^{th} column in 2^{nd} matrix level then use Array_name[6, 4, 2]. Lets see the example for better understanding:

**R CODE**

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# Accessing R Array Elements A <- array(1: 24, dim = c(3, 4, 2)) print(A) # Access the element of 1st row and 2nd column in Matrix 1. print(A[1, 2, 1]) # Access the element of 3rd row and 4th column in in Matrix 2. print(A[3, 4, 2]) # Access only the 3rd row in First Matrix. print(A[3, , 1]) # Access only the 4th column in Second Matrix. print(A[, 4, 2]) # Access the Complete First Matrix. print(A[ , , 1]) # Access the Complete Second Matrix. print(A[ , , 1]) |

**OUTPUT**

### Access All elements of Array in R

In this example we will show you the process of accessing each and every element present in an R Array

**R CODE**

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# Accessing R Array Elements StudentArray <- array(10: 34, dim = c(3, 4, 2)) print(StudentArray) print(paste("Element at StudentArray[1, 1, 1] = ", StudentArray[1, 1, 1])) print(paste("Element at StudentArray[1, 2, 1] = ", StudentArray[1, 2, 1])) print(paste("Element at StudentArray[1, 3, 1] = ", StudentArray[1, 3, 1])) print(paste("Element at StudentArray[1, 4, 1] = ", StudentArray[1, 4, 1])) print(paste("Element at StudentArray[2, 1, 1] = ", StudentArray[2, 1, 1])) print(paste("Element at StudentArray[2, 2, 1] = ", StudentArray[2, 2, 1])) print(paste("Element at StudentArray[2, 3, 1] = ", StudentArray[2, 3, 1])) print(paste("Element at StudentArray[2, 4, 1] = ", StudentArray[2, 4, 1])) print(paste("Element at StudentArray[1, 1, 2] = ", StudentArray[1, 1, 2])) print(paste("Element at StudentArray[1, 2, 2] = ", StudentArray[1, 2, 2])) print(paste("Element at StudentArray[1, 3, 2] = ", StudentArray[1, 3, 2])) print(paste("Element at StudentArray[1, 4, 2] = ", StudentArray[1, 4, 2])) print(paste("Element at StudentArray[2, 1, 2] = ", StudentArray[2, 1, 2])) print(paste("Element at StudentArray[2, 2, 2] = ", StudentArray[2, 2, 2])) print(paste("Element at StudentArray[2, 3, 2] = ", StudentArray[2, 3, 2])) print(paste("Element at StudentArray[2, 4, 2] = ", StudentArray[2, 4, 2])) # To Access Third Row and 1, 2, 3, 4 Columns inside Ist Matrix print(paste("Element at StudentArray[3, 1, 1] = ", StudentArray[3, 1, 1])) print(paste("Element at StudentArray[3, 2, 1] = ", StudentArray[3, 2, 1])) print(paste("Element at StudentArray[3, 3, 1] = ", StudentArray[3, 3, 1])) print(paste("Element at StudentArray[3, 4, 1] = ", StudentArray[3, 4, 1])) # To Access Third Row and 1, 2, 3, 4 Columns inside 2nd Matrix print(paste("Element at StudentArray[3, 1, 1] = ", StudentArray[3, 1, 2])) print(paste("Element at StudentArray[3, 2, 1] = ", StudentArray[3, 2, 2])) print(paste("Element at StudentArray[3, 3, 1] = ", StudentArray[3, 3, 2])) print(paste("Element at StudentArray[3, 4, 1] = ", StudentArray[3, 4, 2])) |

**OUTPUT**

### Accessing Subset of a R Array Elements

In our previous example, we show you, How to access the single element from the R Array. In this example we will show you, How to access subset of multiple items from the Array. To achieve the same we use the R Vector

**TIP:** Negative index position are used to omit those values from Array in R programming

**R CODE**

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# Accessing R Array Elements A <- array(1: 24, dim = c(3, 4, 2)) print(A) # Access the elements of 1st, 3rd row and 2nd, 4th column in Matrix 1. print(A[c(1, 2), c(3, 4), 1]) # Access All the element of 2nd and 3rd row in Matrix 2. print(A[c(2, 3), , 2]) # Access All the element of 1st and 4th Column in Matrix 1. print(A[ , c(1, 4), 1]) # Access All the element except 2nd row and 3rd Columm in Matrix 2. print(A[-2, -3, 2]) |

**OUTPUT**

## R Array Addition and Subtraction

In this example we will show you, How to use R Arithmetic Operators on Matrices to perform arithmetic Operations on Array in R programming.

**R CODE**

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# Adding and Subtracting Elements of Array in R vect1 <- c(10, 20, 40 ) vect2 <- c(55, 67, 89, 96, 100) A <- array(c(vect1, vect2), dim = c(3, 4, 2)) print(A) mat.A <- A[, , 1] mat.B <- A[, , 2] print(mat.A + mat.B) print(mat.B - mat.A) |

**ANALYSIS**

To perform the arithmetic operations, we are converting the multidimensional matrix into one-dimensional matrix.

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mat.A <- A[, , 1] mat.B <- A[, , 2] |

**OUTPUT**

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