R語(yǔ)言 數(shù)組

數(shù)組是可以在兩個(gè)以上維度中存儲(chǔ)數(shù)據(jù)的R數(shù)據(jù)對(duì)象。 例如 - 如果我們創(chuàng)建一個(gè)維度(2，3，4)的數(shù)組，則它創(chuàng)建4個(gè)矩形矩陣，每個(gè)矩陣具有2行和3列。 數(shù)組只能存儲(chǔ)數(shù)據(jù)類型。
使用array()函數(shù)創(chuàng)建數(shù)組。 它使用向量作為輸入，并使用dim參數(shù)中的值創(chuàng)建數(shù)組。

例

以下示例創(chuàng)建一個(gè)由兩個(gè)3x3矩陣組成的數(shù)組，每個(gè)矩陣具有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)

當(dāng)我們執(zhí)行上面的代碼，它產(chǎn)生以下結(jié)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

我們可以使用dimnames參數(shù)給數(shù)組中的行，列和矩陣命名。

# 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)

當(dāng)我們執(zhí)行上面的代碼，它產(chǎn)生以下結(jié)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

訪問(wèn)數(shù)組元素

# 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])

當(dāng)我們執(zhí)行上面的代碼，它產(chǎn)生以下結(jié)果 -

COL1 COL2 COL3 
   3   12   15 
[1] 13
     COL1 COL2 COL3
ROW1    5   10   13
ROW2    9   11   14
ROW3    3   12   15

操作數(shù)組元素

由于數(shù)組由多維構(gòu)成矩陣，所以對(duì)數(shù)組元素的操作通過(guò)訪問(wèn)矩陣的元素來(lái)執(zhí)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)

當(dāng)我們執(zhí)行上面的代碼，它產(chǎn)生以下結(jié)果 -

     [,1] [,2] [,3]
[1,]   10   20   26
[2,]   18   22   28
[3,]    6   24   30

跨數(shù)組元素的計(jì)算

我們可以使用apply()函數(shù)在數(shù)組中的元素上進(jìn)行計(jì)算。

語(yǔ)法

apply(x, margin, fun)

以下是所使用的參數(shù)的說(shuō)明 -

• x是一個(gè)數(shù)組。

• margin是所使用的數(shù)據(jù)集的名稱。

• fun是要應(yīng)用于數(shù)組元素的函數(shù)。

例

我們使用下面的apply()函數(shù)計(jì)算所有矩陣中數(shù)組行中元素的總和。

# 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)

當(dāng)我們執(zhí)行上面的代碼，它產(chǎn)生以下結(jié)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

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