R 语言 数组

  • 数组

    数组数组是R个数据对象,可以存储二维以上的数据。例如-如果我们创建维度为(2、3、4)的数组,则它将创建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()函数创建一个数组。它以向量为输入,并使用dim参数中的值创建一个数组。
    下面的示例创建一个包含两个3x3矩阵的数组,每个矩阵具有3行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)
    
    尝试一下
    当我们执行以上代码时,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参数为数组中的行,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")
    array.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,
       array.names))
    print(result)
    
    尝试一下
    当我们执行以上代码时,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")
    array.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, array.names))
    
    # Print the third row of the second array of the array.
    print(result[3,,2])
    
    # Print the element in the 1st row and 3rd column of the 1st array.
    print(result[1,3,1])
    
    # Print the 2nd Matrix.
    print(result[,,2])
    
    尝试一下
    当我们执行以上代码时,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
    
  • 操纵数组元素

    由于数组是由多维组成的矩阵,因此对数组元素的操作是通过访问矩阵的元素来执行的。
    
    # 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)
    当我们执行以上代码时,它
    
    尝试一下
    当我们执行以上代码时,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()函数对数组中的元素进行计算。
    
    apply(x, margin, fun)
    
    以下是所用参数的描述-
    • x - 是一个数组。
    • margin - 是使用的数据集的名称。
    • fun - 是要应用于数组元素的函数。
    我们使用下面的apply()函数来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)
    
    尝试一下
    当我们执行以上代码时,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