Grand summary warning with multiple rowname columns

[jslatane]

I am trying to make a table with multiple rowname columns and I keep getting warnings. Here's an example, what would be the correct way to do this?

library(gt)
library(dplyr)

# this works without warning
gtcars |> 
	select(mfr, model, hp) |> 
	gt() |> 
	grand_summary_rows(columns = hp, fns = "mean")

# warning messages and mean value in wrong place
gtcars |> 
	select(mfr, model, hp) |> 
	gt(rowname_col = c("mfr", "model")) |>
	grand_summary_rows(columns = hp, fns = "mean")

These are the warnings I get:

Warning messages:
1: In mapply(SIMPLIFY = FALSE, USE.NAMES = FALSE, summary_df[j, ],  :
  longer argument not a multiple of length of shorter
2: In mapply(SIMPLIFY = FALSE, USE.NAMES = FALSE, summary_df[j, ],  :
  longer argument not a multiple of length of shorter
3: In mapply(SIMPLIFY = FALSE, USE.NAMES = FALSE, summary_df[j, ],  :
  longer argument not a multiple of length of shorter
4: In mapply(SIMPLIFY = FALSE, USE.NAMES = FALSE, summary_df[j, ],  :
  longer argument not a multiple of length of shorter

[xanzplug]

The issue is that rowname_col only accepts a single column name, so passing c("mfr", "model") causes the warnings and puts the summary value in the wrong place. You'd need to either combine mfr and model into one column and use that as rowname_col, or keep both as regular columns. gt doesn't support multiple rowname columns through rowname_col.