Question

如何融合包含列表变量的tbl_df？我只是在寻找

的倒数

library( dplyr )

tbl <- data.frame( x = c("A", "A", "B", "B"), y = 1:4 ) %>%
  tbl_df() %>%
  group_by(x) %>%
  do( y = .$y )

tbl
Source: local data frame [2 x 2]
Groups: <by row>

  x        y
1 A <int[2]>
2 B <int[2]>

我想到了像

这样的东西

tbl %>%
  mutate( y = unlist(y) )

Error: incompatible size (2), expecting 1 (the group size) or 1

library( reshape2 )
melt( tbl, id.vars = "x" )

Error: Can't melt data.frames with non-atomic columns

修改这是sessionInfo()

> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-apple-darwin13.1.0 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] graphics  grDevices datasets  stats     utils     methods   base     

other attached packages:
[1] dplyr_0.2     ggplot2_1.0.0 stringr_0.6.2 reshape2_1.4  plyr_1.8.1   

loaded via a namespace (and not attached):
 [1] assertthat_0.1   colorspace_1.2-4 digest_0.6.4     grid_3.1.0       gtable_0.1.2     magrittr_1.0.1   MASS_7.3-33      munsell_0.4.2   
 [9] parallel_3.1.0   proto_0.3-10     Rcpp_0.11.2      scales_0.2.4     tools_3.1.0

在dplyr之后加载了

plyr。

Answer 1

我能想到的最佳选择是使用data.table进行“融化”，如下所示：

library(data.table)
setDT(tbl)[, list(y = unlist(y)), by = x][]
#    x y
# 1: A 1
# 2: A 2
# 3: B 3
# 4: B 4

Answer 2

来自 tidyr 的unnest函数（v.0.1.0.9000）是另一个可以正常运行的选项。

library(tidyr)
unnest(tbl, y)

Source: local data frame [4 x 2]

  x y
1 A 1
2 A 2
3 B 3
4 B 4

您也可以将其直接添加到您的代码链中

data.frame( x = c("A", "A", "B", "B"), y = 1:4 ) %>%
  tbl_df() %>%
  group_by(x) %>%
  do( y = .$y ) %>%
  unnest(y)

熔解列表变量

2 个答案: