Add missing combinations of x and y to a data frame

Source: R/asymmetrise.R

Add rows to df to complete all combinations of columns .x and .y. Importantly, this function observes and maintains any groups created by dplyr::group_by().

add_missing_combinations(df, .x, .y)

Arguments

df

a data frame (or tibble) object
.x, .y

column names to make combinations of

Value

a data frame (or tibble) with additional columns

Examples

df <- data.frame(
  a = c("A", "B"),
  b = c("C", "D"),
  untouched = c(1, 2)
)
df

#>   a b untouched
#> 1 A C         1
#> 2 B D         2

add_missing_combinations(df, a, b)

#>    a b untouched
#> 1  A C         1
#> 2  B D         2
#> 3  A A        NA
#> 4  B A        NA
#> 5  C A        NA
#> 6  D A        NA
#> 7  A B        NA
#> 8  B B        NA
#> 9  C B        NA
#> 10 D B        NA
#> 11 B C        NA
#> 12 C C        NA
#> 13 D C        NA
#> 14 A D        NA
#> 15 C D        NA
#> 16 D D        NA