Kable table R: diagonal cells in bold

Question

Let's say I have a data table:

lttrs <- c('a', 'b', 'c')
a <- c(5, 9, 2)
b <- c(3, 3, 8)
c <- c(14, 2, 0)

df <- as.data.table(cbind(lttrs, a, b, c))

view(df)

       lttrs a b  c
1:     a 5 3 14
2:     b 9 3  2
3:     c 2 8  0

Now I would like to make a table with kable like this:

tableDf <- df[]%>%
  select(everything())%>%
  kable("html", escape = F) %>% 
  kable_styling(bootstrap_options = "striped", full_width = F, position = "left")

Giving me the following image

I would like the diagonal values to be bold in (5, 3, 0). I guess I have to work with cell_spec and have to make a condition in which df$lttrs == colnames(df), however, I have not managed to fix this. Anyone has a solution to it?

user_2761575 · Answer

We can use cell_spec from library(kableExtra)

for (i in df[, seq_len(.N)]) {
  df[i, i+1L] <- cell_spec(df[i, i+1L, with=F], "html", bold=T)
}

kable(df, "html", escape = F) %>% 
  kable_styling(bootstrap_options = "striped", full_width = F)

If you really want things to stand out, you can also change colors and fonts etc. For example,

for (i in df[, seq_len(.N)]) {
  df[i, i+1L] <- cell_spec(df[i, i+1L, with=F], "html", bold=T, background = "red", color = "white")
}

user_10451245 · Answer

Building on the nice answer provided by @dww, a slight adaptation if you are not using integers in your table:

library(kableExtra)

# build the df with non-integers
lttrs <- c('a', 'b', 'c')
a <- c(5.2, 9, 2)
b <- c(3, 3, 8.4)
c <- c(14.3, 2, 0.7)
df <- as.data.frame(cbind(a, b, c))
rownames(df) <- lttrs

# colorize the diagonal elements in table with non-ints
for (i in 1:(ncol(df))) {
  df[i,i] <- cell_spec(df[i, i], bold=T, color = "orange", background = "lightgray")
}

# print table, e.g., in html format
kable(df, "html", escape = F) %>% 
  kable_styling(bootstrap_options = "striped", full_width = F)

Kable table R: diagonal cells in bold

2 Answers