当我想使用group_by()并接着使用nest()命令创建列表列时（如nest()的帮助文件中所示），我得到了意外的结果。当我在未分组的数据帧中使用nest()时，输出是预期的。我还没有找到发生这种情况的原因，但是在我更新到最新的tidyr版本之后就开始了。有解决方案吗？
library(tidyverse)
#> Registered S3 methods overwritten by 'ggplot2':
#> method from
#> [.quosures rlang
#> c.quosures rlang
#> print.quosures rlang
fish_encounters %>%
group_by(fish) %>%
nest()
#> fish data
#> 1 4842 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 2 4843 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 3 4844 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 4 4845 1, 2, 3, 4, 5, 1, 1, 1, 1, 1
#> 5 4847 1, 2, 3, 1, 1, 1
#> 6 4848 1, 2, 3, 4, 1, 1, 1, 1
#> 7 4849 1, 2, 1, 1
#> 8 4850 1, 2, 4, 5, 6, 7, 1, 1, 1, 1, 1, 1
#> 9 4851 1, 2, 1, 1
#> 10 4854 1, 2, 1, 1
#> 11 4855 1, 2, 3, 4, 5, 1, 1, 1, 1, 1
#> 12 4857 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 13 4858 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 14 4859 1, 2, 3, 4, 5, 1, 1, 1, 1, 1
#> 15 4861 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 16 4862 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1
#> 17 4863 1, 2, 1, 1
#> 18 4864 1, 2, 1, 1
#> 19 4865 1, 2, 3, 1, 1, 1
fish_encounters %>%
nest(data = c(station, seen))
#> # A tibble: 19 x 2
#> fish data
#> <fct> <list<df[,2]>>
#> 1 4842 [11 × 2]
#> 2 4843 [11 × 2]
#> 3 4844 [11 × 2]
#> 4 4845 [5 × 2]
#> 5 4847 [3 × 2]
#> 6 4848 [4 × 2]
#> 7 4849 [2 × 2]
#> 8 4850 [6 × 2]
#> 9 4851 [2 × 2]
#> 10 4854 [2 × 2]
#> 11 4855 [5 × 2]
#> 12 4857 [9 × 2]
#> 13 4858 [11 × 2]
#> 14 4859 [5 × 2]
#> 15 4861 [11 × 2]
#> 16 4862 [9 × 2]
#> 17 4863 [2 × 2]
#> 18 4864 [2 × 2]
#> 19 4865 [3 × 2]
sessionInfo()
#> R version 3.6.0 (2019-04-26)
#> Platform: x86_64-apple-darwin15.6.0 (64-bit)
#> Running under: macOS Sierra 10.12.6
#>
#> Matrix products: default
#> BLAS: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRblas.0.dylib
#> LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib
#>
#> locale:
#> [1] de_CH.UTF-8/de_CH.UTF-8/de_CH.UTF-8/C/de_CH.UTF-8/de_CH.UTF-8
#>
#> attached base packages:
#> [1] stats graphics grDevices utils datasets methods base
#>
#> other attached packages:
#> [1] forcats_0.4.0 stringr_1.4.0 dplyr_0.8.3 purrr_0.3.2
#> [5] readr_1.3.1 tidyr_0.8.3.9000 tibble_2.1.3 ggplot2_3.1.1
#> [9] tidyverse_1.2.1
#>
#> loaded via a namespace (and not attached):
#> [1] Rcpp_1.0.1 cellranger_1.1.0 plyr_1.8.4 pillar_1.4.2
#> [5] compiler_3.6.0 highr_0.8 tools_3.6.0 zeallot_0.1.0
#> [9] digest_0.6.20 lubridate_1.7.4 jsonlite_1.6 evaluate_0.14
#> [13] nlme_3.1-140 gtable_0.3.0 lattice_0.20-38 pkgconfig_2.0.2
#> [17] rlang_0.4.0.9000 cli_1.1.0 yaml_2.2.0 haven_2.1.0
#> [21] xfun_0.7 withr_2.1.2 xml2_1.2.0 httr_1.4.0
#> [25] knitr_1.23 hms_0.4.2 generics_0.0.2 vctrs_0.2.0
#> [29] grid_3.6.0 tidyselect_0.2.5 glue_1.3.1 R6_2.4.0
#> [33] fansi_0.4.0 readxl_1.3.1 rmarkdown_1.13 modelr_0.1.4
#> [37] magrittr_1.5 backports_1.1.4 scales_1.0.0 htmltools_0.3.6
#> [41] rvest_0.3.4 assertthat_0.2.1 colorspace_1.4-1 utf8_1.1.4
#> [45] stringi_1.4.3 lazyeval_0.2.2 munsell_0.5.0 broom_0.5.2
#> [49] crayon_1.3.4
由reprex package（v0.3.0）于2019-08-22创建
答案 0 :(得分：0)
似乎这与tidyr的dev版本内部有关，其中nest()返回data.frame而不是小标题。参见https://github.com/tidyverse/tidyr/issues/675。
这样做可以克服
fish_encounters %>%
group_by(fish) %>%
nest() %>%
as_tibble()
您可以使用以下方法重新安装vctrs以解决该问题：
remotes::install_github("r-lib/vctrs")
然后重新启动R。