Bug Report: as_flex_table doesn't pass multi-column/row footnote coordinates correctly

[geneh0]

I want to add footnotes throughout all levels of a variable and across a couple columns. Then I want to convert it to a flextable. I get an error at the as_flex_table stage.

I think it's because during the creation of the flextable, (something that creates flextable_calls) it tries to create footnotes that reference at all permutations of i and j. However, flextable uses the pairwise combination of i and j:

flextable::footnotes

Symbols are added to the cells designated by the selection i and j. If you use i = c(1,3) and j = c(2,5), then you will add the symbols (or the repeated symbol) to cells [1,2] and [3,5].

In addition to the example error below, I'm noticing that some other tables will only have flextable footnotes in alternating rows because of the way i and j are expanded.

library(dplyr)
library(gtsummary)

trial %>% 
  tbl_summary(by = trt, 
              include = c(age,
                          stage,
                          grade)) %>% 
  modify_table_styling(columns = c(stat_1, stat_2),
                       rows = (variable %in% "grade") & (row_type == "level"),
                       footnote = "Cell-level foonotes here.") %>% 
  as_flex_table()
#> Error in data.frame(i = i, j = j): arguments imply differing number of rows: 3, 2

^{Created on 2024-11-08 with reprex v2.1.1}

When debugging as_flex_table

Browse[2]> flextable_calls$footnote
[[1]]
flextable::footnote(i = 1L, j = 2:3, value = flextable::as_paragraph("Median (IQR); n (%)"), 
    part = "header", ref_symbols = 1L)

[[2]]
flextable::footnote(i = 9:11, j = 2:3, value = flextable::as_paragraph("Cell-level foonotes here."), 
    part = "body", ref_symbols = 2L)

[ddsjoberg]

Thank you for the report and the reprex! I am surprised this hasn't been reported long ago...these lines of code haven't been touched in years. Much appreciated! This should be addressed in #2063