创建一个data.frame，其列将在每一行中保存一个列表

Question

我无法创建一个由一组字符组成的列的数据框。

这不可能/我应该坚持列表吗？

>subsets <- c(list("a","d","e"),list("a","b","c","e")) 
customerids <- c(1,1) 
transactions <- data.frame(customerid = customerids,subset =subsets) 
> str(transactions) 
'data.frame': 2 obs. of 8 variables: 
$ customerid : num 1 1 
$ subset..a. : Factor w/ 1 level "a": 1 1 
$ subset..d. : Factor w/ 1 level "d": 1 1 
$ subset..e. : Factor w/ 1 level "e": 1 1 
$ subset..a..1: Factor w/ 1 level "a": 1 1 
$ subset..b. : Factor w/ 1 level "b": 1 1 
$ subset..c. : Factor w/ 1 level "c": 1 1 
$ subset..e..1: Factor w/ 1 level "e": 1 1 

Answer 1

我觉得你写subsets错误。如果是这样的事实：

subsets <- list(c("a", "d", "e"), c("a", "b", "c", "e")) 
# [[1]] 
# [1] "a" "d" "e" 

# [[2]] 
# [1] "a" "b" "c" "e" 

而且customerids是c(1,1)，那么你可以有subsets为列表中的一个data.frame列作为行的总数仍然是相同的。可以按如下方式做到这一点：

DF <- data.frame(id = customerids, value = I(subsets)) 
# id  value 
# 1 1 a, d, e 
# 2 1 a, b, c, e 

sapply(DF, class) 
#  id  value 
# "numeric" "AsIs" 

现在您可以访问DF$value和执行操作，你会在list。

Answer 2

使用data.table代替：

library(data.table) 

# note the extra list here 
subsets <- list(list("a","d","e"),list("a","b","c","e")) 
customerids <- c(1,1) 

transactions <- data.table(customerid = customerids, subset = subsets) 
str(transactions) 
#Classes ‘data.table’ and 'data.frame': 2 obs. of 2 variables: 
# $ customerid: num 1 1 
# $ subset :List of 2 
# ..$ :List of 3 
# .. ..$ : chr "a" 
# .. ..$ : chr "d" 
# .. ..$ : chr "e" 
# ..$ :List of 4 
# .. ..$ : chr "a" 
# .. ..$ : chr "b" 
# .. ..$ : chr "c" 
# .. ..$ : chr "e" 
# - attr(*, ".internal.selfref")=<externalptr> 

transactions 
# customerid subset 
#1:   1 <list> 
#2:   1 <list>