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本文小編為大家詳細(xì)介紹“R語(yǔ)言怎么創(chuàng)建數(shù)組”,內(nèi)容詳細(xì),步驟清晰,細(xì)節(jié)處理妥當(dāng),希望這篇“R語(yǔ)言怎么創(chuàng)建數(shù)組”文章能幫助大家解決疑惑,下面跟著小編的思路慢慢深入,一起來(lái)學(xué)習(xí)新知識(shí)吧。
數(shù)組(array)是向量和矩陣的推廣,是多維(三維或三維以上)數(shù)據(jù)。與向量和矩陣一樣,數(shù)組的元素必須也是同一類型的數(shù)據(jù)。例如 - 如果我們創(chuàng)建一個(gè)維度(2,3,4)的數(shù)組,則會(huì)創(chuàng)建4個(gè)矩形矩陣,每個(gè)矩陣具有2行和3列。
在R中,一般用array()函數(shù)來(lái)創(chuàng)建數(shù)組。array()的原型為:
array(data = NA, dim = length(data), dimnames = NULL)
其中:data給定數(shù)組元素,默認(rèn)情況下是NA;dim用來(lái)指定數(shù)組的維度,默認(rèn)情況下是一維數(shù)組;dimnames設(shè)定各維度的名稱,必須是個(gè)列表,默認(rèn)情況下無(wú)名稱。
例如創(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(2,3,5) vector2 <- c(7,8,9,11,11,12) # Take these vectors as input to the array. result <- array(c(vector1,vector2),dim = c(3,3,2)) print(result)
運(yùn)行以上的代碼,輸出結(jié)果如下:
, , 1 [,1] [,2] [,3] [1,] 2 7 11 [2,] 3 8 11 [3,] 5 9 12 , , 2 [,1] [,2] [,3] [1,] 2 7 11 [2,] 3 8 11 [3,] 5 9 12
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(2,3,5) vector2 <- c(7,8,9,11,11,12) 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)
運(yùn)行以上的代碼,輸出結(jié)果如下:
, , Matrix1 COL1 COL2 COL3 ROW1 2 7 11 ROW2 3 8 11 ROW3 5 9 12 , , Matrix2 COL1 COL2 COL3 ROW1 2 7 11 ROW2 3 8 11 ROW3 5 9 12
有關(guān)如何訪問(wèn)數(shù)組元素,請(qǐng)參考以下代碼實(shí)現(xiàn) -
# Create two vectors of different lengths. vector1 <- c(2,3,5) vector2 <- c(7,8,9,11,11,12) 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])
運(yùn)行以上的代碼,輸出結(jié)果如下:
COL1 COL2 COL3 5 9 12 [1] 11 COL1 COL2 COL3 ROW1 2 7 11 ROW2 3 8 11 ROW3 5 9 12
由于數(shù)組是由多個(gè)維度組成的矩陣,通過(guò)訪問(wèn)矩陣的元素來(lái)執(zhí)行數(shù)組元素的相關(guān)操作。
# Create two vectors of different lengths. vector1 <- c(2,3,5) vector2 <- c(7,8,9,11,11,12) # 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(4,1,0) vector4 <- c(6,0,7,3,13,3,2,8,9) 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)
運(yùn)行以上的代碼,輸出結(jié)果如下:
[,1] [,2] [,3] [1,] 4 14 22 [2,] 6 16 22 [3,] 10 18 24
我們可以使用apply()函數(shù)對(duì)數(shù)組中的元素進(jìn)行計(jì)算。語(yǔ)法
apply(x, margin, fun)
以下是使用的參數(shù)的描述 -
x - 是一個(gè)數(shù)組。
margin - 是使用的數(shù)據(jù)集的名稱。
fun - 是應(yīng)用于數(shù)組元素的函數(shù)。
例子使用下面的apply()函數(shù)來(lái)計(jì)算所有矩陣中數(shù)組的行中的元素的總和。
# Create two vectors of different lengths. vector1 <- c(2,3,5) vector2 <- c(7,8,9,11,11,12) # 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)
運(yùn)行以上的代碼,輸出結(jié)果如下:
, , 1 [,1] [,2] [,3] [1,] 2 7 11 [2,] 3 8 11 [3,] 5 9 12 , , 2 [,1] [,2] [,3] [1,] 2 7 11 [2,] 3 8 11 [3,] 5 9 12 [1] 40 44 52
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