Array
An array is a natural extension to a matrix in its number of dimensions. More specifically, an array is a vector that is represented and accessible in a given number of dimensions (mostly more than two dimensions).
If you are already familiar with vectors and matrices, you won't be surprised to see how arrays behave.
Creating an array
To create an array, we call array() by supplying a vector of data, how this data is arranged in different dimensions, and sometimes the names of the rows and columns of these dimensions.
Suppose we have some data (10 integers from 0 to 9) and we need to arrange them in three dimensions: 1 for the first dimension, 5 for the second, and 2 for the third:
a1 <- array(c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), dim = c(1, 5, 2)) a1 ## , , 1 ## ## [,1] [,2] [,3] [,4] [,5] ## [1,] 0 1 2 3 4 ## ## , , 2 ## ## [,1] [,2] [,3] [,4] [,5] ## [1,] 5 6 7 8 9
We can clearly see how we can access these entries by looking at the notations...
