R flextable - How to add a table-wide horizontal border under a merged cell

问题

Is there a smart way to have a horizontal border table wide when you have merged cells? (In the example below, it is not yet table wide).

Or should I write a function to calculate the correct index?

library(flextable)
library(officer)
library(dplyr)

myft <- flextable(head(mtcars), 
                  col_keys = c("am", "carb", "gear", "mpg", "drat" ))%>% 
  theme_vanilla()%>%
  merge_v(j = c("am"))%>%border(border.bottom = fp_border(style = "solid", width=2), i=c(3,6), part="body")

myft

回答1:

Here is a code for what you want. It needs more work to be generic - the example is only adapted when column 1 is the only that has merged cells.

library(flextable)
library(officer)
library(dplyr)

bigborder <- fp_border(style = "solid", width=2)
myft <- flextable(head(mtcars), 
                  col_keys = c("am", "carb", "gear", "mpg", "drat" ))%>% 
  theme_vanilla()%>%
  merge_v(j = c("am")) 

# here starts the trick
row_loc <- rle(cumsum( myft$body$spans$columns[,1] ))$values
myft <- myft %>% 
  border(border.bottom = bigborder, i=row_loc, j = 2:5, part="body") 
myft <- myft %>% 
  border(border.bottom = bigborder, 
         i = myft$body$spans$columns[,1] > 1, j = 1, part="body") %>% 


  border(border.bottom = bigborder, border.top = bigborder, part = "header")
myft

来源：https://stackoverflow.com/questions/44700492/r-flextable-how-to-add-a-table-wide-horizontal-border-under-a-merged-cell