How to write a quotient, with horizontal line, in a cell of a table in R

I want that in the quotient n_i/c_i, instead of the line being oblique, the line is horizontal. I try to use "\frac{}" but I get an error.
I attach image and code of the quotient with the oblique line.

library(grid)
library(gridExtra)
library(glue)
data1P <- data.frame(c("[1, 5)", "[5, 7)", "[7, 9)", "[9, 10]"), 
            c("6", "7" ,"22" ,"23"),
            c("4", "2", "2", "1"),
            c("1.5", "3.5", "11" , "23"))

colnames(data1P) <- lapply(list("X\\Y= [1,4)","n[i]","c[i]","d[i]==paste(n[i]/c[i])"),glue)

tt <- ttheme_default(colhead=list(fg_params = list(parse=TRUE)))

grid.newpage()

grid.table(data1P, rows = NULL, theme=tt)

>Solution :

The language being used for the column names isn’t LaTeX, where "\frac{}" would work, it’s plotmath from R graphics, so the syntax is different. Your code works for me with this change:

colnames(data1P) <- lapply(list("X\\Y= [1,4)","n[i]","c[i]","d[i]==frac(n[i],c[i])"),glue)

i.e. use frac(n[i], c[i]) to get the fraction.