forestplot_color_by_significance.R

library(forestplot)

data(mtcars)
mtcars$disp <- mtcars$disp/100

coefs <- summary(mod <- lm(mpg ~ disp + cyl + qsec + wt, data = mtcars))$coeff
cis <- confint(mod)

dat <- data.frame(cbind(coefs[, c(1, 4)], cis))
names(dat) <- c("mean", "pv", "lower", "upper")
dat <- dat[-1, ] # Drop intercept
dat$var <- rownames(dat)


# Inside `local` because of the <<-, to avoid polluting
fn <- local({
  i <- 0
  clrs <- ifelse(dat$pv < .05, "darkgreen",
                 ifelse(dat$pv < .1, "darkblue",
                    "darkgrey"))

  function(..., clr.line, clr.marker) {
    i <<- i + 1
    fpDrawNormalCI(..., clr.line = clrs[i], clr.marker = clrs[i])
  }
})


forestplot(dat,
           labeltext = var,
           fn.ci_norm = fn,
           boxsize = .2
           ) |>
  fp_set_style(txt_gp = fpTxtGp(ticks = gpar(fontfamily = "", cex = 1))) |>
  fp_set_zebra_style("#EFEFEF")