Used to store multiple elements of the same data type under a single identifier. They can be accessed using an index that starts from 0
# Creating a 3D array
arr3d <- array(1:24, dim = c(2, 3, 4))
# A 3D array with dimensions 2 x 3 x 4
We can access the arrays with index number inside a [] bracket.
# Accessing elements
arr3d <- array(1:24, dim = c(2, 3, 4))
element <- arr3d[1, 2, 3]
element
Operators are used in arrays to perform various operations.
Operation
Syntax
Description
Example
Addition
arr1 + arr2
Element-wise addition of two vectors.
array(1:24, dim = c(2, 3, 4)) + array(24:48, dim = c(2, 3, 4))
Subtraction
arr1 - arr2
Element-wise subtraction of one vector from another.
array(1:24, dim = c(2, 3, 4)) - array(24:48, dim = c(2, 3, 4))
Multiplication
arr * scalar or arr1 * arr2
Scalar multiplication or element-wise multiplication.
array(1:24, dim = c(2, 3, 4)) * 2
Division
arr / scalar or arr1 / arr2
Scalar division or element-wise division.
array(1:24, dim = c(2, 3, 4)) / 2
Exponentiation
arr^exp
Element-wise exponentiation.
array(1:24, dim = c(2, 3, 4))^2
array(1:24, dim = c(2, 3, 4)) + array(24:48, dim = c(2, 3, 4))
array(1:24, dim = c(2, 3, 4)) - array(24:48, dim = c(2, 3, 4))
array(1:24, dim = c(2, 3, 4))*2
array(1:24, dim = c(2, 3, 4))/2
array(1:24, dim = c(2, 3, 4))^2
Functions are a built in methods that performs operations fast and easy.
Operation
Syntax
Description
Example
Dimensions
dim(arr)
Returns the dimensions of an array.
dimensions <- dim(arr3d)
Sum
sum(arr)
Calculates the sum of all elements in an array.
arr_sum_all <- sum(arr3d)
Mean
mean(arr)
Calculates the mean (average) of elements in an array.
arr_mean <- mean(arr3d)
Length
length(arr)
Applies a function to the specified margins of an array.
arr_length <- length(arr3d)
Applying a Function
apply(arr, margin, fun)
Applies a function to the specified margins of an array.
row_sums <- apply(arr3d, 1:2, sum)
Array Flattening
arr^exp
Flattens an array into a one-dimensional vector.
flattened_vector <- as.vector(arr3d)
arr3d <- array(1:24, dim = c(2, 3, 4))
dim(arr3d)
sum(arr3d)
mean(arr3d)
length(arr3d)
apply(arr3d, 1:2, sum)
as.vector(arr3d)
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