Arrays and Matrices in R | Lecture 3

Arrays and Matrices in R

Arrays are declared in R using the dim() or array() functions. 

For example:

> mycarsale.array<-1:30

> mycarsale.array

 [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16

[17] 17 18 19 20 21 22 23 24 25 26 27 28 29 30

The above command allocates a vector of 1 to 30 to the variable array called mycarsale.array 

To make it as a matrix, we can use dim() function as given below 

> dim(mycarsale.array)<-c(3,5,2)

> mycarsale.array

, , 1

     [,1] [,2] [,3] [,4] [,5]

[1,]    1    4    7   10   13

[2,]    2    5    8   11   14

[3,]    3    6    9   12   15

, , 2

     [,1] [,2] [,3] [,4] [,5]

[1,]   16   19   22   25   28

[2,]   17   20   23   26   29

[3,]   18   21   24   27   30

In the above output 3 indicates the number of columns, 5 indicate the number of columns and 2 indicates the number of tables.

Array in R

> mycarsale.array[2,3,1]

[1] 8

> mycarsale.array[2,3,2]

[1] 23