将嵌套列表转换为数据框 [英] Converting nested list to dataframe

问题描述

目标是将有时包含丢失记录的嵌套列表转换为数据框架。缺少记录的结构示例是：

The goal is to convert a nested list which sometimes contain missing records into a data frame. An example of the structure when there are missing records is:

str(mylist)

List of 3
 $ :List of 7
  ..$ Hit    : chr "True"
  ..$ Project: chr "Blue"
  ..$ Year   : chr "2011"
  ..$ Rating : chr "4"
  ..$ Launch : chr "26 Jan 2012"
  ..$ ID     : chr "19"
  ..$ Dept   : chr "1, 2, 4"
 $ :List of 2
  ..$ Hit  : chr "False"
  ..$ Error: chr "Record not found"
 $ :List of 7
  ..$ Hit    : chr "True"
  ..$ Project: chr "Green"
  ..$ Year   : chr "2004"
  ..$ Rating : chr "8"
  ..$ Launch : chr "29 Feb 2004"
  ..$ ID     : chr "183"
  ..$ Dept   : chr "6, 8"

当没有丢失记录时，可以使用数据将列表转换为数据框.frame（do.call（rbind.data.frame，mylist））。但是，当记录丢失时，会导致列不匹配。我知道有一些功能来合并不匹配列的数据帧，但是我还没有找到可以应用于列表的数据帧。理想的结果将保留所有变量的记录2与NA。希望有一些帮助。

When there are no missing records the list can be converted into a data frame using data.frame(do.call(rbind.data.frame, mylist)). However, when records are missing this results in a column mismatch. I know there are functions to merge data frames of non-matching columns but I'm yet to find one that can be applied to lists. The ideal outcome would keep record 2 with NA for all variables. Hoping for some help.

编辑添加 dput（mylist）：

list(structure(list(Hit = "True", Project = "Blue", Year = "2011", 
Rating = "4", Launch = "26 Jan 2012", ID = "19", Dept = "1, 2, 4"), .Names = c("Hit", 
"Project", "Year", "Rating", "Launch", "ID", "Dept")), structure(list(
Hit = "False", Error = "Record not found"), .Names = c("Hit", 
"Error")), structure(list(Hit = "True", Project = "Green", Year = "2004", 
Rating = "8", Launch = "29 Feb 2004", ID = "183", Dept = "6, 8"), .Names = c("Hit", 
"Project", "Year", "Rating", "Launch", "ID", "Dept")))

推荐答案

您还可以使用（至少v1.9.3） rbindlist 在 data.table 包中：

You can also use (at least v1.9.3) of rbindlist in the data.table package:

library(data.table)

rbindlist(mylist, fill=TRUE)

##      Hit Project Year Rating      Launch  ID    Dept            Error
## 1:  True    Blue 2011      4 26 Jan 2012  19 1, 2, 4               NA
## 2: False      NA   NA     NA          NA  NA      NA Record not found
## 3:  True   Green 2004      8 29 Feb 2004 183    6, 8               NA

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