类似于列表列表中的expand.grid

Question

我有三个文本文档存储为名为"dlist"的列表列表:

dlist <- structure(list(name = c("a", "b", "c"), text = list(c("the", "quick", "brown"), c("fox", "jumps", "over", "the"), c("lazy", "dog"))), .Names = c("name", "text"))

在我的脑海中,我发现像这样的图片列表很有帮助:

   name  text
1  a     c("the", "quick", "brown")
2  b     c("fox", "jumps", "over", "the")
3  c     c("lazy", "dog")

如何操纵如下？想法是绘制图形,因此可以为ggplot2融化的东西会很好.

  name  text
1    a   the
2    a quick
3    a brown
4    b   fox
5    b jumps
6    b  over
7    b   the
8    c  lazy
9    c   dog

这是每个单词一行,同时给出单词及其父文档.

我试过了:

> expand.grid(dlist)
  name                  text
1    a     the, quick, brown
2    b     the, quick, brown
3    c     the, quick, brown
4    a fox, jumps, over, the
5    b fox, jumps, over, the
6    c fox, jumps, over, the
7    a             lazy, dog
8    b             lazy, dog
9    c             lazy, dog

> sapply(seq(1,3), function(x) (expand.grid(dlist$name[[x]], dlist$text[[x]])))
     [,1]     [,2]     [,3]    
Var1 factor,3 factor,4 factor,2
Var2 factor,3 factor,4 factor,2

unlist(dlist)
  name1   name2   name3   text1   text2   text3   text4 
    "a"     "b"     "c"   "the" "quick" "brown"   "fox" 
  text5   text6   text7   text8   text9 
"jumps"  "over"   "the"  "lazy"   "dog"

> sapply(seq(1,3), function(x) (cbind(dlist$name[[x]], dlist$text[[x]])))
[[1]]
     [,1] [,2]   
[1,] "a"  "the"  
[2,] "a"  "quick"
[3,] "a"  "brown"

[[2]]
     [,1] [,2]   
[1,] "b"  "fox"  
[2,] "b"  "jumps"
[3,] "b"  "over" 
[4,] "b"  "the"  

[[3]]
     [,1] [,2]  
[1,] "c"  "lazy"
[2,] "c"  "dog" 

可以说我被各种apply和plyr函数迷惑了,并且真的不知道从哪里开始.我从来没有见过像上面的"sapply"尝试那样的结果,也不理解它.

Answer 1

如果将您转换dlist为命名列表(在我看来是一个更适合的结构),您可以使用stack()获取所需的两列data.frame.

(第二行中的rev()和setNames()调用只是调整列排序和名称以匹配问题中显示的所需输出的众多方法之一.)

x <- setNames(dlist$text, dlist$name)
setNames(rev(stack(x)),  c("name", "text"))
#   name  text
# 1    a   the
# 2    a quick
# 3    a brown
# 4    b   fox
# 5    b jumps
# 6    b  over
# 7    b   the
# 8    c  lazy
# 9    c   dog