CODEWITHSUNDEEP
rtidyr
John-Henry
John-Henry

Reputation: 1807

`unnest_longer` two columns as once?

I have a dataframe with two sets of columns v and t amongst others.

  library(tidyverse)
(df <-   
tibble(id = 1, 
       v1 = 1, v2 = 2, v3 = 3,
       t1 = "a", t2 = "b", t3 = "c"
       )
)
#> # A tibble: 1 × 7
#>      id    v1    v2    v3 t1    t2    t3   
#>   <dbl> <dbl> <dbl> <dbl> <chr> <chr> <chr>
#> 1     1     1     2     3 a     b     c

I want my output to be three rows long. I think one way I can do this is by nesting the similar columns, and unnest_longer. But this is not allowed.

  ## unnest_longer can't handle multiple cols
df %>% 
  nest(v = c(v1, v2, v3),
       t = c(t1, t2, t3)) %>% 
  unnest_longer(c("v", "t"))
#> Error: Must extract column with a single valid subscript.
#> x Subscript `var` has size 2 but must be size 1.

Is it possible to unnest_longer multiple columns at once?

Upvotes: 0

Views: 291

Answers (1)

akrun
akrun

Reputation: 887223

According to the documentation of ?unnest_longer takes only a single column

.col, col - List-column to extract components from.

whereas the argument in unnest is cols (which can unnest more than one column)

Perhaps, the OP wanted to use pivot_longer instead of nest/unnest i.e. reshape to 'long' format by specifying the cols without the 'id' column, return the .value and capture the non digits (\\D+) in the column name as names_pattern

library(dplyr)
library(tidyr)
df %>%
     pivot_longer(cols = -id, names_to = ".value", 
        names_pattern = "^(\\D+).*")
# A tibble: 3 × 3
#     id     v t    
#  <dbl> <dbl> <chr>
#1     1     1 a    
#2     1     2 b    
#3     1     3 c

Upvotes: 1

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