Unnesting a list of lists in a data frame column
Note: Ignore the original and Update 1; Update 2 is better with the current state of the tidyverse.
Original:
With purrr
, which is nice for lists,
library(purrr)
df %>% dmap(unlist)
## # A tibble: 2 x 2
## x y
## <dbl> <dbl>
## 1 1 1
## 2 1 2
which is more or less equivalent to
as.data.frame(lapply(df, unlist))
## x y
## a 1 1
## b 1 2
Update 1:
dmap
has been deprecated and moved to purrrlyr, the home of interesting but ill-fated functions that will now shout lots of deprecation warnings at you. You could translate the base R idiom to tidyverse:
df %>% map(unlist) %>% as_tibble()
which will work fine for this case, but not for more than one row (a problem all these approaches face). A more robust solution might be
library(tidyverse)
df %>% bind_rows(df) %>% # make larger sample data
mutate_if(is.list, simplify_all) %>% # flatten each list element internally
unnest() # expand
#> # A tibble: 4 × 2
#> x y
#> <dbl> <dbl>
#> 1 1 1
#> 2 1 2
#> 3 1 1
#> 4 1 2
Update 2:
At some point since this was asked, tidyr::unnest()
got updated such that it doesn't error anymore, so you can just do
df %>%
unnest(y) %>%
unnest(y)
#> # A tibble: 2 × 2
#> x y
#> <dbl> <dbl>
#> 1 1 1
#> 2 1 2
If you care about the names in the list, pull them out first and then unnest the names and the list at the same time:
df %>%
mutate(label = map(y, names)) %>%
unnest(c(y, label)) %>%
unnest(y)
#> # A tibble: 2 × 3
#> x y label
#> <dbl> <dbl> <chr>
#> 1 1 1 a
#> 2 1 2 b
I'll leave the previous answers for continuity, but this is simpler.
This can be done in a simple step using unnest_longer()
since tidyr 1.0.0 :
df <- tibble::tibble(
x = 1,
y = list(list(a = 1, b = 2))
)
library(tidyr)
unnest_longer(df,y,indices_include = FALSE)
#> # A tibble: 2 x 2
#> x y
#> <dbl> <dbl>
#> 1 1 1
#> 2 1 2
Created on 2019-09-14 by the reprex package (v0.3.0)