kableExtra_squared.R

kable(foo, format = "latex", booktabs = T, row.names = FALSE, linesep = "", escape = FALSE) %>%
  kable_styling(latex_options = c("striped")) %>%
  group_rows("$\\\\text{Group1}^a$", 1, 2, escape = FALSE) %>% 
  group_rows(paste0("Group2\\\\", footnote_marker_alphabet(1), sep = ""), 3, 4, escape = FALSE) %>% 
  # I don't think expression() is helpful, doesn't seem to get converted
  # to latex
  group_rows(expression("Group3"^a), 5, 6) %>% 
  group_rows("Group4\\\\textsuperscript{a}", 7, 8, escape = FALSE)


# To add Greek symbols
 kable(foo) %>%   
    add_header_above(c(" " = 6, "$\\lambda$" = 4), escape = FALSE)