Unnest a recursive data frame

Usage

unnest_tree(
  x,
  id_col,
  child_col,
  level_to = "level",
  parent_to = "parent",
  ancestors_to = NULL
)

Arguments

x: (data.frame) The data frame to unnest.
id_col: (character(1), integer(1), or symbol) The column that uniquely identifies each observation.
child_col: (character(1), integer(1), or symbol) The column that contains the children of an observation. This column must be a list where each element is either NULL or a data frame with the same columns as x.
level_to: (character(1)) The column name ("level" by default) in which to store the level of an observation. Use NULL if you don't need this information.
parent_to: (character(1)) The column name ("parent" by default) in which to store the parent id of an observation. Use NULL if you don't need this information.
ancestors_to: (character(1)) The column name (NULL by default) in which to store the ids of the ancestors of a deeply nested child. Use NULL if you don't need this information.

Value

A "flat" data frame.

Examples

df <- tibble(
  id = 1L,
  name = "a",
  children = list(
    tibble(
      id = 11:12,
      name = c("b", "c"),
      children = list(
        NULL,
        tibble(
          id = 121:122,
          name = c("d", "e")
        )
      )
    )
  )
)
df
#> # A tibble: 1 × 3
#>      id name  children        
#>   <int> <chr> <list>          
#> 1     1 a     <tibble [2 × 3]>

unnest_tree(
  df,
  id_col = "id",
  child_col = "children",
  level_to = "level",
  parent_to = "parent",
  ancestors_to = "ancestors"
)
#> # A tibble: 5 × 5
#>      id name  level parent ancestors
#>   <int> <chr> <int>  <int> <list>   
#> 1     1 a         1     NA <NULL>   
#> 2    11 b         2      1 <int [1]>
#> 3    12 c         2      1 <int [1]>
#> 4   121 d         3     12 <int [2]>
#> 5   122 e         3     12 <int [2]>