将嵌套列表折叠到方括号中

Question

我正在寻找一个函数，将具有任意长度和级别数的嵌套列表转换为一个字符串，该字符串可以作为来自 LaTeX 包 forest 的树的输入。

以下是我的进展情况。我设法将树中的每个无子节点括在方括号中，但如何检索中间节点的名称并将它们连接成一个字符串？

forest 环境中的字符串显示了我想将示例列表转换成的内容。

\documentclass[a4paper]{article}
\usepackage{forest}
\begin{document}
<<list>>=
library("tidyverse")
nestedlist <- list("A"=list("B"=45:50, "C"=LETTERS[21:26],
    "D"=list("E"=7:10, "F"=list("G","H"))))                   
squarebrackets <- function(x){
    if(class(x) == "list")
        map(x, squarebrackets)
    else
        paste0("[",x,"]") %>%
            paste0(., collapse="")
}

squarebrackets(nestedlist)
@
\begin{forest}
[A[B[45][46][47][48][49][50]][C[U][V][W][X][Y][Z]][D[E[7][8][9][10]][F[G][H]]]]
\end{forest}
\end{document}

Answer 1

一种方法是利用 unlist() 自动创建的名称层次结构。这也将使 F=c("G", "H") 和 F=list("G", "H") 以相同的方式处理。

以下示例不允许在节点名称中使用数字，并且节点名称必须是唯一的。这也许可以通过使用 rapply() 方法来改进。

定义备选方案squarebrackets

squarebracketsAlt <- function(inlist){

  #create the name hierarchy
  storeList <- unlist(inlist)

  #get unique names which represents levels in hierarchy
  uniqueNames <- unique(unlist(strsplit(gsub("[0-9]", "", names(storeList)), "\.")))

  #keep the names to search for length of node brackets
  vecNames <- names(storeList)
  storeVec <- paste0("[", storeList, "]")
  names(storeVec) <- vecNames

  for(i in  uniqueNames){

    #determine the two positions of the node brackets
    whereBrack <- grep(paste0("\.",i, "\."),
                       paste0(".", gsub("[0-9]", "", names(storeVec)), "."))

    #add the start bracket and node name to vector
    storeVec <- append(storeVec, paste0("[", i), after=(whereBrack[1]-1))
    #add the end bracket to vector
    storeVec <- append(storeVec, paste0("]") , after=(whereBrack[length(whereBrack)]+1))


  }
  #collapse and output
  cat(paste(storeVec, collapse=""))

}

在你的嵌套列表上试试：

nestedlist <- list("A"=list("B"=45:50, "C"=LETTERS[21:26],
                            "D"=list("E"=7:10, "F"=list("G","H")))) 

squarebracketsAlt(nestedlist)

输出：

[A[B[45][46][47][48][49][50]][C[U][V][W][X][Y][Z]][D[E[7][8][9][10]][F[G][H]]]]

示例更大的层次结构：

nestedlist1 <- list("Ad fe"=list("B"=45:50, "C"=list("U"=letters[1:10],LETTERS[22:26]),
                                "D"=list("E"=7:10, "F"=list("G"=list("ZZ foo"=list("AA bar"=c(1:10),2,3,4,5)),"H", "C"))))  

squarebracketsAlt(nestedlist1)

输出：

[Ad fe[B[45][46][47][48][49][50]][C[U[a][b][c][d][e][f][g][h][i][j]][V][W][X][Y][Z]][D[E[7][8][9][10]][F[G[ZZ foo[AA bar[1][2][3][4][5][6][7][8][9][10]][2][3][4][5]]][H][C]]]]

现实生活中的例子：

nestedlist2 <- list("Main Area"=
                     list("Fishing vessel"=c("trawler", "line", "skipper"), "Oil tanker"=c("Large", "Small", "Medium size"=
                          list("Barents Sea", "Norwegian Sea", "Kara Sea", "Greenland"))))
squarebracketsAlt(nestedlist2)

输出：

[Main Area[Fishing vessel[trawler][line][skipper]][Oil tanker[Large][Small][Medium size[Barents Sea][Norwegian Sea][Kara Sea][Greenland]]]]

前导数字示例：

squarebracketsAltNum <- function(inlist){

  #create the name hierarchy
  storeList <- unlist(inlist)

  #get unique names which represents levels in hierarchy
  uniqueNames <- unique(paste(gsub("[A-z].*", "", unlist(strsplit(names(storeList), "\."))),
                              unlist(strsplit(gsub("[0-9]", "", names(storeList)), "\.")), sep=""))

  #keep the names to search for length of node brackets
  vecNames <- names(storeList)
  storeVec <- paste0("[", storeList, "]")
  names(storeVec) <- vecNames
  k <- 1

  for(i in  uniqueNames){
    cat(i, "\n")
    #determine the two positions of the node brackets
    whereBrack <- grep(paste0("\.",i),
                       paste0(".", names(storeVec)))

    #change position of number and character
    namePaster <- unique(paste(unlist(strsplit(gsub("[0-9]", "", names(storeList)), "\.")),
                               gsub("[A-z].*", "", unlist(strsplit(names(storeList), "\."))), sep=""))[k]


    #add the start bracket and node name to vector
    storeVec <- append(storeVec, paste0("[", namePaster), after=(whereBrack[1]-1))
    #add the end bracket to vector
    storeVec <- append(storeVec, paste0("]") , after=(whereBrack[length(whereBrack)]+1))
    k <- k+1

  }
  #collapse and output
  cat(paste(storeVec, collapse=""))

}

数字和word/sentence之间没有space。 Fiddle 用正则表达式修复：

nestedlist <- list("100A"=list("4B"=45:50, "3C"=LETTERS[21:26],
                               "D"=list("E"=7:10, "78F"=c("G","H"))))          
squarebracketsAlt(nestedlist)

输出：

[A100[B4[45][46][47][48][49][50]][C3[U][V][W][X][Y][Z]][D[E[7][8][9][10]][F78[G][H]]]]

将嵌套列表折叠到方括号中

Collapse nested list into square brackets

r

list

knitr