返回嵌套级别和值的嵌套列表

Question

我想使用networkD3可视化一些深层嵌套的数据.在发送之前,我无法弄清楚如何将数据转换成正确的格式radialNetwork.

以下是一些示例数据:

level <- c(1, 2, 3, 4, 4, 3, 4, 4, 1, 2, 3)
value <- letters[1:11]

where level表示嵌套的级别,value是节点的名称.通过使用这两个向量,我需要将数据转换为以下格式:

my_list <- list(
  name = "root",
  children = list(
    list(
      name = value[1], ## a
      children = list(list(
        name = value[2], ## b
        children = list(list(
          name = value[3], ## c
          children = list(
            list(name = value[4]), ## d
            list(name = value[5]) ## e
          )
        ),
        list(
          name = value[6], ## f
          children = list(
            list(name = value[7]), ## g
            list(name = value[8]) ## h
          )
        ))
      ))
    ),
    list(
      name = value[9], ## i
      children = list(list(
        name = value[10], ## j
        children = list(list(
          name = value[11] ## k
        ))
      ))
    )
  )
)

这是解除对象:

> dput(my_list)
# structure(list(name = "root",
#                children = list(
#                  structure(list(
#                    name = "a",
#                    children = list(structure(
#                      list(name = "b",
#                           children = list(
#                             structure(list(
#                               name = "c", children = list(
#                                 structure(list(name = "d"), .Names = "name"),
#                                 structure(list(name = "e"), .Names = "name")
#                               )
#                             ), .Names = c("name",
#                                           "children")), structure(list(
#                                             name = "f", children = list(
#                                               structure(list(name = "g"), .Names = "name"),
#                                               structure(list(name = "h"), .Names = "name")
#                                             )
#                                           ), .Names = c("name",
#                                                         "children"))
#                           )), .Names = c("name", "children")
#                    ))
#                  ), .Names = c("name",
#                                "children")), structure(list(
#                                  name = "i", children = list(structure(
#                                    list(name = "j", children = list(structure(
#                                      list(name = "k"), .Names = "name"
#                                    ))), .Names = c("name",
#                                                    "children")
#                                  ))
#                                ), .Names = c("name", "children"))
#                )),
#           .Names = c("name",
#                      "children"))

然后我可以将它传递给最终的绘图功能:

library(networkD3)
radialNetwork(List = my_list)

输出看起来类似于:

---

问题:如何创建嵌套列表？

注意:正如@ zx8754所指出的,在这篇SO帖子中已经有了一个解决方案,但这需要data.frame作为输入.由于我的不一致level,我没有看到一个简单的方法将其转换为data.frame.

Answer 1

使用data.table-style 合并：

library(data.table)
dt = data.table(idx=1:length(value), level, parent=value)

dt = dt[dt[, .(i=idx, level=level-1, child=parent)], on=.(level, idx < i), mult='last']

dt[is.na(parent), parent:= 'root'][, c('idx','level'):= NULL]

> dt
#     parent child
#  1:   root     a
#  2:      a     b
#  3:      b     c
#  4:      c     d
#  5:      c     e
#  6:      b     f
#  7:      f     g
#  8:      f     h
#  9:   root     i
# 10:      i     j
# 11:      j     k

现在我们可以使用其他帖子中的解决方案：

x = maketreelist(as.data.frame(dt))

> identical(x, my_list)
# [1] TRUE