Let's say I have a nested df, and I want to unnest the columns:
df <- tibble::tribble(
~x, ~y, ~nestdf,
1, 2, tibble::tibble(a=1:2, b=3:4),
3, 4, tibble::tibble(a=3:5, b=5:7)
)
tidyr::unnest(df, nestdf)
# x y a b
# <dbl> <dbl> <int> <int>
#1 1 2 1 3
#2 1 2 2 4
#3 3 4 3 5
#4 3 4 4 6
#5 3 4 5 7
The result has the x and y columns extended to match the dimensions of nestdf, with the new rows using the existing values. However, I want the new rows to contain NA, like so:
# x y a b
# <dbl> <dbl> <int> <int>
#1 1 2 1 3
#2 NA NA 2 4
#3 3 4 3 5
#4 NA NA 4 6
#5 NA NA 5 7
Is it possible to do this with unnest? Either the first or last row for each group can be kept as non-NA, I don't mind.
Repeating rows, and binding with an unnest of the nested list column(s):
nr <- sapply(df$nestdf, nrow) - 1
cbind(
df[rep(rbind(seq_along(nr), NA), rbind(1, nr)), c("x","y")],
unnest(df["nestdf"], cols=everything())
)
# x y a b
#1 1 2 1 3
#2 NA NA 2 4
#3 3 4 3 5
#4 NA NA 4 6
#5 NA NA 5 7