讀寫Texual format

• dput()、dget()

  直接演示：

  > x <- data.frame(foo = 1:4, bar = c("a", "b", "c", "d"))
  > dput(x, file = "D:\\test")
  > dput(x)# 如果file = ""，則輸出到console
  structure(list(foo = 1:4, bar = structure(1:4, .Label = c("a", "b", "c", "d"), class = "factor")), .Names = c("foo", "bar"), row.names = c(NA, -4L), class = "data.frame")
  > dget("D:\\test")
    foo bar
  1   1   a
  2   2   b
  3   3   c
  4   4   d
  

• dump()、source()

  有什麼比直接演示還明白的呢？

  > x <- data.frame(foo = 1:4, bar = c("a", "b", "c", "d"))
  > y <- "abc"
  #把x、y存到test裡面，dump第一個參數是vector，元素是由Objest名稱(string)，第二個參數是存檔path。
  > dump(c("x", "y"), file = "D:\\test")
  #把x、y物件從執行環境中刪除
  > rm(x, y)
  > x
  Error: object 'x' not found
  > y
  Error: object 'y' not found
  #再載入存有x、y物件的檔案到目前執行環境
  > source("D:\\test")
  #解構x看看，這時候x就存在了
  > unclass(x)
  $foo
  [1] 1 2 3 4
  
  $bar
  [1] a b c d
  Levels: a b c d
  
  attr(,"row.names")
  [1] 1 2 3 4