使用array()函数创建数组。 它使用向量作为输入，并使用dim参数中的值创建数组。
例
以下示例创建一个由两个3x3矩阵组成的数组，每个矩阵具有3行和3列。
# Create two vectors of different lengths. vector1 <- c(5,9,3) vector2 <- c(10,11,12,13,14,15) # Take these vectors as input to the array. result <- array(c(vector1,vector2),dim = c(3,3,2)) print(result)
当我们执行上面的代码，它产生以下结果 -
, , 1
[,1] [,2] [,3]
[1,] 5 10 13
[2,] 9 11 14
[3,] 3 12 15
, , 2
[,1] [,2] [,3]
[1,] 5 10 13
[2,] 9 11 14
[3,] 3 12 15
命名列和行
我们可以使用dimnames参数给数组中的行，列和矩阵命名。
# Create two vectors of different lengths.
vector1 <- c(5,9,3)
vector2 <- c(10,11,12,13,14,15)
column.names <- c("COL1","COL2","COL3")
row.names <- c("ROW1","ROW2","ROW3")
matrix.names <- c("Matrix1","Matrix2")
# Take these vectors as input to the array.
result <- array(c(vector1,vector2),dim = c(3,3,2),dimnames = list(row.names,column.names,
matrix.names))
print(result)
当我们执行上面的代码，它产生以下结果 -
, , Matrix1
COL1 COL2 COL3
ROW1 5 10 13
ROW2 9 11 14
ROW3 3 12 15
, , Matrix2
COL1 COL2 COL3
ROW1 5 10 13
ROW2 9 11 14
ROW3 3 12 15
访问数组元素
# Create two vectors of different lengths.
vector1 <- c(5,9,3)
vector2 <- c(10,11,12,13,14,15)
column.names <- c("COL1","COL2","COL3")
row.names <- c("ROW1","ROW2","ROW3")
matrix.names <- c("Matrix1","Matrix2")
# Take these vectors as input to the array.
result <- array(c(vector1,vector2),dim = c(3,3,2),dimnames = list(row.names,
column.names, matrix.names))
# Print the third row of the second matrix of the array.
print(result[3,,2])
# Print the element in the 1st row and 3rd column of the 1st matrix.
print(result[1,3,1])
# Print the 2nd Matrix.
print(result[,,2])
当我们执行上面的代码，它产生以下结果 -
COL1 COL2 COL3
3 12 15
[1] 13
COL1 COL2 COL3
ROW1 5 10 13
ROW2 9 11 14
ROW3 3 12 15
操作数组元素
由于数组由多维构成矩阵，所以对数组元素的操作通过访问矩阵的元素来执行。
# Create two vectors of different lengths. vector1 <- c(5,9,3) vector2 <- c(10,11,12,13,14,15) # Take these vectors as input to the array. array1 <- array(c(vector1,vector2),dim = c(3,3,2)) # Create two vectors of different lengths. vector3 <- c(9,1,0) vector4 <- c(6,0,11,3,14,1,2,6,9) array2 <- array(c(vector1,vector2),dim = c(3,3,2)) # create matrices from these arrays. matrix1 <- array1[,,2] matrix2 <- array2[,,2] # Add the matrices. result <- matrix1+matrix2 print(result)
当我们执行上面的代码，它产生以下结果 -
[,1] [,2] [,3] [1,] 10 20 26 [2,] 18 22 28 [3,] 6 24 30
跨数组元素的计算
我们可以使用apply()函数在数组中的元素上进行计算。
语法
apply(x, margin, fun)
以下是所使用的参数的说明 -
x是一个数组。
margin是所使用的数据集的名称。
fun是要应用于数组元素的函数。
例
我们使用下面的apply()函数计算所有矩阵中数组行中元素的总和。
# Create two vectors of different lengths. vector1 <- c(5,9,3) vector2 <- c(10,11,12,13,14,15) # Take these vectors as input to the array. new.array <- array(c(vector1,vector2),dim = c(3,3,2)) print(new.array) # Use apply to calculate the sum of the rows across all the matrices. result <- apply(new.array, c(1), sum) print(result)
当我们执行上面的代码，它产生以下结果 -
, , 1
[,1] [,2] [,3]
[1,] 5 10 13
[2,] 9 11 14
[3,] 3 12 15
, , 2
[,1] [,2] [,3]
[1,] 5 10 13
[2,] 9 11 14
[3,] 3 12 15
[1] 56 68 60