close

Reading data from files

read.table() 或是 scan()

利用read.table讀取houses.txt

   1: > HousePrice <- read.table("C:\\statistics R\\houses.txt")
   2: > HousePrice
   3:    Price Floor Area Rooms Age Cent.heat
   4: 01 52.00   111  830     5 6.2        no
   5: 02 54.75   128  710     5 7.5        no
   6: 03 57.50   101 1000     5 4.2        no
   7: 04 57.50   131  690     6 8.8        no
   8: 05 59.75    93  900     5 1.9       yes

取出Price行資料

   1: > HousePrice[1]
   2:    Price
   3: 01 52.00
   4: 02 54.75
   5: 03 57.50
   6: 04 57.50
   7: 05 59.75

取出Floor行資料

   1: > HousePrice[2]
   2:    Floor
   3: 01   111
   4: 02   128
   5: 03   101
   6: 04   131
   7: 05    93

如果要取出其中一筆資料呢? 例如HousePrice第一行中的第一筆和第二筆資料:

   1: >  HousePrice[[1]][1]
   2: [1] 52
   3: >  HousePrice[[1]][2]
   4: [1] 54.75

The scan() function

假設第1行為character 第2,3行為numeric資料

image

利用scan()讀取input.txt

   1: > inp <- scan("C:\\statistics R\\input.txt", list("",0,0))
   2: Read 5 records
   3: > inp
   4: [[1]]
   5: [1] "Jane"  "Peter" "John"  "Ryan"  "Irene"
   6:  
   7: [[2]]
   8: [1] 52.00 54.75 57.50 57.50 59.75
   9:  
  10: [[3]]
  11: [1] 111 128 101 131  93

假設John的第一筆資料無法取得, 請填入NA

利用scan()讀取input2.txt

image

讀入的資料存成三個變數分別為label, x, y

   1: > label <- inp[[1]]; x <- inp[[2]]; y <- inp[[3]]
   2: > label
   3: [1] "Jane"  "Peter" "John"  "Ryan"  "Irene"
   4: > x
   5: [1] 52.00 54.75    NA 57.50 59.75
   6: > y
   7: [1] 111 128 101 131  93

另外, 可以在scan下參數指定回傳的變數名稱, 分別為 name, x1, x2

   1: > inp <- scan("C:\\statistics R\\input2.txt", list(name="",x1=0,x2=0))
   2: Read 5 records

取出來的方式有三種:

方法1: variable_name$fieldname

   1: > inp$name
   2: [1] "Jane"  "Peter" "John"  "Ryan"  "Irene"
   3: > inp$x1
   4: [1] 52.00 54.75    NA 57.50 59.75
   5: > inp$x2

方法2 variable_name[“fieldname”]

   1: > inp["name"]
   2: $name
   3: [1] "Jane"  "Peter" "John"  "Ryan"  "Irene"
   4:  
   5: > inp["x1"]
   6: $x1
   7: [1] 52.00 54.75    NA 57.50 59.75
   8:  
   9: > inp["x2"]
  10: $x2
  11: [1] 111 128 101 131  93

方法3: variable_name[ index ]

   1: > inp[[1]]
   2: [1] "Jane"  "Peter" "John"  "Ryan"  "Irene"
   3: > inp[[2]]
   4: [1] 52.00 54.75    NA 57.50 59.75
   5: > inp[[3]]
   6: [1] 111 128 101 131  93

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data()可以列出R提供內建的資料庫

image

假設欲載入infert資料可以下指令data(infert), 接著下ls()指令觀察目前workspace所有變數名稱

   1: > data()
   2: > data(infert)
   3: > ls()
   4: [1] "HousePrice" "infert"     "inp"        "label"      "x"          "y"


image

編輯edit()

   1: > edit(x)

image

   1: > edit(inp)

image

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