List to dataframe v2

cyl.4 <- mtcars %>% filter(cyl==4) %>% select(-cyl)
cyl.6 <- mtcars %>% filter(cyl==6) %>% select(-cyl)
mtcars.list <- list("4"=cyl.4,"6"=cyl.6)
mtcars.list
## $`4`
##                 mpg  disp  hp drat    wt  qsec vs am gear carb
## Datsun 710     22.8 108.0  93 3.85 2.320 18.61  1  1    4    1
## Merc 240D      24.4 146.7  62 3.69 3.190 20.00  1  0    4    2
## Merc 230       22.8 140.8  95 3.92 3.150 22.90  1  0    4    2
## Fiat 128       32.4  78.7  66 4.08 2.200 19.47  1  1    4    1
## Honda Civic    30.4  75.7  52 4.93 1.615 18.52  1  1    4    2
## Toyota Corolla 33.9  71.1  65 4.22 1.835 19.90  1  1    4    1
## Toyota Corona  21.5 120.1  97 3.70 2.465 20.01  1  0    3    1
## Fiat X1-9      27.3  79.0  66 4.08 1.935 18.90  1  1    4    1
## Porsche 914-2  26.0 120.3  91 4.43 2.140 16.70  0  1    5    2
## Lotus Europa   30.4  95.1 113 3.77 1.513 16.90  1  1    5    2
## Volvo 142E     21.4 121.0 109 4.11 2.780 18.60  1  1    4    2
## 
## $`6`
##                 mpg  disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4      21.0 160.0 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag  21.0 160.0 110 3.90 2.875 17.02  0  1    4    4
## Hornet 4 Drive 21.4 258.0 110 3.08 3.215 19.44  1  0    3    1
## Valiant        18.1 225.0 105 2.76 3.460 20.22  1  0    3    1
## Merc 280       19.2 167.6 123 3.92 3.440 18.30  1  0    4    4
## Merc 280C      17.8 167.6 123 3.92 3.440 18.90  1  0    4    4
## Ferrari Dino   19.7 145.0 175 3.62 2.770 15.50  0  1    5    6

using bind_rows(.id)

mtcars.list %>% bind_rows(.id="cyl")
##                cyl  mpg  disp  hp drat    wt  qsec vs am gear carb
## Datsun 710       4 22.8 108.0  93 3.85 2.320 18.61  1  1    4    1
## Merc 240D        4 24.4 146.7  62 3.69 3.190 20.00  1  0    4    2
## Merc 230         4 22.8 140.8  95 3.92 3.150 22.90  1  0    4    2
## Fiat 128         4 32.4  78.7  66 4.08 2.200 19.47  1  1    4    1
## Honda Civic      4 30.4  75.7  52 4.93 1.615 18.52  1  1    4    2
## Toyota Corolla   4 33.9  71.1  65 4.22 1.835 19.90  1  1    4    1
## Toyota Corona    4 21.5 120.1  97 3.70 2.465 20.01  1  0    3    1
## Fiat X1-9        4 27.3  79.0  66 4.08 1.935 18.90  1  1    4    1
## Porsche 914-2    4 26.0 120.3  91 4.43 2.140 16.70  0  1    5    2
## Lotus Europa     4 30.4  95.1 113 3.77 1.513 16.90  1  1    5    2
## Volvo 142E       4 21.4 121.0 109 4.11 2.780 18.60  1  1    4    2
## Mazda RX4        6 21.0 160.0 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag    6 21.0 160.0 110 3.90 2.875 17.02  0  1    4    4
## Hornet 4 Drive   6 21.4 258.0 110 3.08 3.215 19.44  1  0    3    1
## Valiant          6 18.1 225.0 105 2.76 3.460 20.22  1  0    3    1
## Merc 280         6 19.2 167.6 123 3.92 3.440 18.30  1  0    4    4
## Merc 280C        6 17.8 167.6 123 3.92 3.440 18.90  1  0    4    4
## Ferrari Dino     6 19.7 145.0 175 3.62 2.770 15.50  0  1    5    6
?bind_rows() # read ".id" part

using enframe() and unnest()

mtcars.list %>% enframe() %>% unnest(value)
## # A tibble: 18 × 11
##    name    mpg  disp    hp  drat    wt  qsec    vs    am  gear  carb
##    <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
##  1 4      22.8 108      93  3.85  2.32  18.6     1     1     4     1
##  2 4      24.4 147.     62  3.69  3.19  20       1     0     4     2
##  3 4      22.8 141.     95  3.92  3.15  22.9     1     0     4     2
##  4 4      32.4  78.7    66  4.08  2.2   19.5     1     1     4     1
##  5 4      30.4  75.7    52  4.93  1.62  18.5     1     1     4     2
##  6 4      33.9  71.1    65  4.22  1.84  19.9     1     1     4     1
##  7 4      21.5 120.     97  3.7   2.46  20.0     1     0     3     1
##  8 4      27.3  79      66  4.08  1.94  18.9     1     1     4     1
##  9 4      26   120.     91  4.43  2.14  16.7     0     1     5     2
## 10 4      30.4  95.1   113  3.77  1.51  16.9     1     1     5     2
## 11 4      21.4 121     109  4.11  2.78  18.6     1     1     4     2
## 12 6      21   160     110  3.9   2.62  16.5     0     1     4     4
## 13 6      21   160     110  3.9   2.88  17.0     0     1     4     4
## 14 6      21.4 258     110  3.08  3.22  19.4     1     0     3     1
## 15 6      18.1 225     105  2.76  3.46  20.2     1     0     3     1
## 16 6      19.2 168.    123  3.92  3.44  18.3     1     0     4     4
## 17 6      17.8 168.    123  3.92  3.44  18.9     1     0     4     4
## 18 6      19.7 145     175  3.62  2.77  15.5     0     1     5     6

Session Info

sessionInfo()
## R version 3.6.2 (2019-12-12)
## Platform: x86_64-apple-darwin15.6.0 (64-bit)
## Running under: macOS  10.16
## 
## 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] 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] stats     graphics  grDevices utils     datasets  methods   base     
## 
## other attached packages:
## [1] forcats_0.5.2   stringr_1.4.1   dplyr_1.0.10    purrr_0.3.5    
## [5] readr_2.1.3     tidyr_1.2.1     tibble_3.1.8    ggplot2_3.3.6  
## [9] tidyverse_1.3.2
## 
## loaded via a namespace (and not attached):
##  [1] tidyselect_1.2.0    xfun_0.34           bslib_0.4.0        
##  [4] haven_2.5.1         gargle_1.2.1        colorspace_2.0-3   
##  [7] vctrs_0.5.0         generics_0.1.3      htmltools_0.5.3    
## [10] yaml_2.3.6          utf8_1.2.2          rlang_1.0.6        
## [13] jquerylib_0.1.4     pillar_1.8.1        withr_2.5.0        
## [16] glue_1.6.2          DBI_1.1.3           dbplyr_2.2.1       
## [19] readxl_1.4.1        modelr_0.1.9        lifecycle_1.0.3    
## [22] munsell_0.5.0       blogdown_1.13       gtable_0.3.1       
## [25] cellranger_1.1.0    rvest_1.0.3         evaluate_0.17      
## [28] knitr_1.40          tzdb_0.3.0          fastmap_1.1.0      
## [31] fansi_1.0.3         broom_1.0.1         backports_1.4.1    
## [34] scales_1.2.1        googlesheets4_1.0.1 cachem_1.0.6       
## [37] jsonlite_1.8.3      fs_1.5.2            hms_1.1.2          
## [40] digest_0.6.30       stringi_1.7.8       bookdown_0.29      
## [43] grid_3.6.2          cli_3.4.1           tools_3.6.2        
## [46] magrittr_2.0.3      sass_0.4.2          crayon_1.5.2       
## [49] pkgconfig_2.0.3     ellipsis_0.3.2      xml2_1.3.3         
## [52] reprex_2.0.2        lubridate_1.8.0     googledrive_2.0.0  
## [55] httr_1.4.4          assertthat_0.2.1    rmarkdown_2.17     
## [58] rstudioapi_0.14     R6_2.5.1            compiler_3.6.2