将数据框转换为深度嵌套的列表 [英] Converting data frame into deeply nested list

问题描述

我正在尝试创建whisker软件包期望的数据结构，但似乎无法弄清楚 从我的数据框创建该结构.假设我有以下数据框:

I'm trying to create a data structure that the whisker package expects, and I can't seem to figure out how create that structure from my data frame. Let's say I have the following data frame:

library(dplyr)  

existing_format <- 
  mtcars %>% 
    select(carb, gear, cyl) %>% 
    arrange(carb, gear, cyl) %>% 
    distinct() 

...我想从existing_format转到以下所需格式(仅显示desired_format列表的前两个元素):

...I would like to go from existing_format to the following desired format (only first two elements of desired_format list are shown):

desired_format <- list(
  list( 
    carb = "1",
    gear = list(
      list(gear = "3", cyl = list(list(cyl = "4"), list(cyl = "6"))),
      list(gear = "4", cyl = list(list(cyl = "4")))
    )
  ),
  list( 
    carb = "2",
    gear = list(
      list(gear = "3", cyl = list(list(cyl = "8"))),
      list(gear = "4", cyl = list(list(cyl = "4"))),
      list(gear = "5", cyl = list(list(cyl = "4")))
    )
  )
)

我尝试过按carb和gear分组的方法，然后使用tidyr::nest()创建嵌套的df，但是没有任何反应.某事告诉我whisker::iteratelist()或whisker::rowSplit()是前进的方向，但我无法弄清楚.

I've tried things like grouping by carb and gear, then using tidyr::nest() to create a nested df, but nothing is doing. Something tells me that whisker::iteratelist() or whisker::rowSplit() is the way forward, but I can't figure it out.

谢谢， 克里斯

推荐答案

在这种情况下，也许比它需要的灵活得多，但是您可以进行递归拆分

Perhaps more flexible than it needs to be in this case, but you can do a recursive split

rsplit<-function(dd) {
  col <- names(dd)[1]
  dat <- dd[[1]]
  xx <- lapply(unique(dat), function(x) {
    z <- setNames(list(x), col)
    if(ncol(dd)>1) {
      z[[names(dd)[2]]] <- rsplit(dd[dat==x,-1, drop=FALSE])
    }
    z
  })
  xx
}

rsplit(existing_format)

这将拆分所有列，并使用列标题中的名称.

This will split on all the columns and use the names from the column headers.

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