在 data.frame 的列中解包和合并列表 [英] Unpacking and merging lists in a column in data.frame

问题描述

我有以下 data.frame:

id     name   altNames
1001   Joan   character(0)      
1002   Jane   c("Janie", "Janet", "Jan")
1003   John   Jon
1004   Bill   Will
1005   Tom    character(0)      

altNames 列可以为空(即字符(0))，只有一个名称，或名称列表.我想要的是一个 data.frame (或一个列表)，其中来自 name 和/或 altNames 的每个条目与相应的条目一起只出现一次id，像这样:

The column altNames could be empty (i.e. character(0)), have just one name, or a list of names. What I want is a data.frame (or a list) where each entry from name and/or altNames appears just once along with the corresponding id, like this:

id     name
1001   Joan
1002   Jane
1002   Janie
1002   Janet
1002   Jan
1003   John
1003   Jon
1004   Bill
1004   Will
1005   Tom

最有效的方法是什么?更好的是使用 dplyr.谢谢

What's the most efficient way of doing it? Even better is dplyr is utilized. Thanks

这是数据:

df <- data_frame(
  id = c("1001", "1002","1003", "1004", "1005"), 
  name = c("Joan", "Jane", "John", "Bill", "Tom"), 
  altNames = list(character(0), c("Janie", "Janet", "Jan"), "Jon", "Will", character(0))
)

推荐答案

这是一个可能的 data.table 方法

Here's a possible data.table approach

library(data.table)
setDT(dat)[, .(name = c(name, unlist(altNames))), by = id]
#       id  name
#  1: 1001  Joan
#  2: 1002  Jane
#  3: 1002 Janie
#  4: 1002 Janet
#  5: 1002   Jan
#  6: 1003  John
#  7: 1003   Jon
#  8: 1004  Bill
#  9: 1004  Will
# 10: 1005   Tom

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