A special index for nested tibble

[timliu]

I am used to working with nested columns whose each row looks like <tibble [1 x 1]>

However, a function produced the list column with each row of the following format:
<tibble[,1] [1 × 1]>. How should I interpret the structure of such list columns and how can I turn the latter format to a format that is similar to <tibble [1 x 1]>?

reprex:

Local .Rprofile detected at /lustre/scratch123/hgi/mdt1/teams/martin/tl11/elgh_prs/.Rprofile

library(tibble)

#> Warning: package 'tibble' was built under R version 3.6.3

library(purrr)

library(dplyr)

#> Warning: replacing previous import 'vctrs::data_frame' by 'tibble::data_frame'

#> when loading 'dplyr'

#> 

#> Attaching package: 'dplyr'

#> The following objects are masked from 'package:stats':

#> 

#>     filter, lag

#> The following objects are masked from 'package:base':

#> 

#>     intersect, setdiff, setequal, union

mutate(tibble(a=1),b = map(a, ~ tibble(c=1)))

#> # A tibble: 1 x 2

#>       a b                   

#>   <dbl> <list>              

#> 1     1 <tibble[,1] [1 × 1]>

^{Created on 2021-04-20 by the reprex package (v2.0.0)}

Session info

sessioninfo::session_info()

#> ─ Session info ───────────────────────────────────────────────────────────────

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#> 

#> [1] /nfs/users/nfs_t/tl11/R/x86_64-conda_cos6-linux-gnu-library/3.6

#> [2] /lustre/scratch119/realdata/mdt2/teams/martin/users/tl11/conda_env/renv_renv/lib/R/library

[technocrat]

map returns a list, which is the reason that the b column of the tibble is a list.

suppressPackageStartupMessages({
  library(dplyr)
  library(purrr)
})

tib <- tibble(a=1,b = map(a, ~ tibble(c=1)))

tib
#> # A tibble: 1 x 2
#>       a b                   
#>   <dbl> <list>              
#> 1     1 <tibble[,1] [1 × 1]>

str(tib)
#> tibble[,2] [1 × 2] (S3: tbl_df/tbl/data.frame)
#>  $ a: num 1
#>  $ b:List of 1
#>   ..$ : tibble[,1] [1 × 1] (S3: tbl_df/tbl/data.frame)
#>   .. ..$ c: num 1

tib %>% mutate(c = unlist(b))
#> # A tibble: 1 x 3
#>       a b                        c
#>   <dbl> <list>               <dbl>
#> 1     1 <tibble[,1] [1 × 1]>     1

[timliu]

Thanks for the reply!

I think what I want is <tibble [1 x 1]> and not completely it to a double. Do you know how I can do that? (I am using an older version of tibble here)
`

library(tidyverse)
tibble(a=1)  %>% 
    mutate(b = map(a, ~ tibble(c=1)))
#> # A tibble: 1 x 2
#>       a b               
#>   <dbl> <list>          
#> 1     1 <tibble [1 x 1]>

^{Created on 2021-04-21 by the reprex package (v1.0.0)}

Session info

sessioninfo::session_info()
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[technocrat]

The example from the documentation shows that although tibbles can contain tibbles the enclosed tibbles display as the class of the innermost layer.

suppressPackageStartupMessages({
  library(tibble)
})
# Tibbles can contain columns that are tibbles or matrices
# if the number of rows is compatible. Unnamed tibbled are
# spliced, i.e. the inner columns are inserted into the
# tibble under construction.
tib <- tibble(
  a = 1:3,
  tibble(
    b = 4:6,
    c = 7:9
  ),
  d = tibble(
    e = tibble(
      f = b
    )
  ))

tib
#> # A tibble: 3 x 4
#>       a     b     c d$e$f
#>   <int> <int> <int> <int>
#> 1     1     4     7     4
#> 2     2     5     8     5
#> 3     3     6     9     6

str(tib[4])
#> tibble[,1] [3 × 1] (S3: tbl_df/tbl/data.frame)
#>  $ d: tibble[,1] [3 × 1] (S3: tbl_df/tbl/data.frame)
#>   ..$ e: tibble[,1] [3 × 1] (S3: tbl_df/tbl/data.frame)
#>   .. ..$ f: int [1:3] 4 5 6

[davis]

The objects you are seeing in both the old and new versions of tibble are the same. The fact that they print differently is a bug introduced by the CRAN version of pillar. It has been fixed in the dev version.