Can I unnest a list column directly into n columns?
The list can be assumed to regular, with all elements being of equal length.
If instead of a list column I would have a character vector, I could tidyr::separate. I can tidyr::unnest, but we need another helper variable to be able to tidyr::spread. Am I missing an obvious method?
Example data:
library(tibble)
df1 <- data_frame(
gr = c('a', 'b', 'c'),
values = list(1:2, 3:4, 5:6)
)
# A tibble: 3 x 2 gr values <chr> <list> 1 a <int [2]> 2 b <int [2]> 3 c <int [2]>
Goal:
df2 <- data_frame(
gr = c('a', 'b', 'c'),
V1 = c(1, 3, 5),
V2 = c(2, 4, 6)
)
# A tibble: 3 x 3 gr V1 V2 <chr> <dbl> <dbl> 1 a 1. 2. 2 b 3. 4. 3 c 5. 6.
Current method:
unnest(df1) %>%
group_by(gr) %>%
mutate(r = paste0('V', row_number())) %>%
spread(r, values)
with tidyr 1.0.0 you can do :
library(tidyr)
df1 <- tibble(
gr = c('a', 'b', 'c'),
values = list(1:2, 3:4, 5:6)
)
unnest_wider(df1, values)
#> New names:
#> * `` -> ...1
#> * `` -> ...2
#> New names:
#> * `` -> ...1
#> * `` -> ...2
#> New names:
#> * `` -> ...1
#> * `` -> ...2
#> # A tibble: 3 x 3
#> gr ...1 ...2
#> <chr> <int> <int>
#> 1 a 1 2
#> 2 b 3 4
#> 3 c 5 6
Created on 2019-09-14 by the reprex package (v0.3.0)
The output is verbose here because the elements that were unnested horizontally (the vector elements) were not named, and unnest_wider doesn't want to guess silently.
We can name them beforehand to avoid it :
df1 %>%
dplyr::mutate(values = purrr::map(values, setNames, c("V1","V2"))) %>%
unnest_wider(values)
#> # A tibble: 3 x 3
#> gr V1 V2
#> <chr> <int> <int>
#> 1 a 1 2
#> 2 b 3 4
#> 3 c 5 6
Or just use suppressMessages() or purrr::quietly()