Arrays
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2023-12-01
数组是R数据对象,可以存储两个以上的数据。 例如 - 如果我们创建一个维度(2,3,4)数组,那么它会创建4个矩形矩阵,每个矩阵有2行3列。 数组只能存储数据类型。
使用array()函数创建array() 。 它将矢量作为输入,并使用dim参数中的值来创建数组。
例子 (Example)
以下示例创建一个包含两个3x3矩阵的数组,每个矩阵包含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时,它会产生以下结果 -
, , 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参数为数组中的行,列和矩阵dimnames 。
# 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时,它会产生以下结果 -
, , 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 (Accessing Array Elements)
# 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时,它会产生以下结果 -
COL1 COL2 COL3
3 12 15
[1] 13
COL1 COL2 COL3
ROW1 5 10 13
ROW2 9 11 14
ROW3 3 12 15
操纵数组元素
由于数组由多维构成矩阵,因此通过访问矩阵的元素来执行对数组元素的操作。
# 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时,它会产生以下结果 -
[,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()函数对数组中的元素进行计算。
语法 (Syntax)
apply(x, margin, fun)
以下是所用参数的说明 -
x是一个数组。
margin是使用的数据集的名称。
fun是要跨数组元素应用的函数。
例子 (Example)
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时,它会产生以下结果 -
, , 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