An **array** is nothing more than a **matrix with more than two dimensions**. It is basically a series of two-dimensional matrices “on top of each other”; in other words, a matrix is an array with only two dimensions, or only one layer. To build an array, there is a function called… `array()`

, and inside that function, you’ll need to use the option `dim`

(dimension) to organize the number of rows, columns… and layers. In the following example, we build an array called `long.box`

made of 4 rows, 3 columns and 2 layers, and containing the values ranging from 1 to 24:

[code language=”r”]

long.box <- array(1:24, dim=c(4,3,2))

long.box

[/code]

As seen on the picture above, we obtain 2 matrices each containing 12 values arranged in 4 rows and 3 columns. Each matrix or layer of the array is identify by its “layer number” following 2 commas `, , 1`

and `, , 2`

. Logically, the first layer contains data ranging from 1 to 12 and the second layer contains values from 13 to 24.