Feature request/suggestion - point estimate with interval labels to aid in plotting

I've found it very useful to have easy access to a 'label' providing a chosen point estimate and density interval, which can be added for example to graphs as a means of providing extra, concise information about a parameter or effect that is depicted. E.g., adding label with the median and 95% HDI from the posterior, or whatever other point estimate/interval you choose, in the form: 5.67 [4.33 - 6.01].

The following R code takes a posterior distribution in the form of a vector and returns a summary. You can ignore most of the probably very inelegant coding, but the function inside of this function called 'point.uncertainty' could be a useful place to begin if you think this feature may be useful.

This requires dplyr and hdinterval packages to run.

summarise.me <- function(posterior, name = "summary", interval = .95, p.e = "median", u.e = "hdi") {
  
  hdi.bounds <- hdi(posterior, credMass = interval)
  hdi.lower <- hdi.bounds["lower"]
  hdi.upper <- hdi.bounds["upper"]
  
  eti.upper <- quantile(posterior, probs = interval + ((1 - interval) / 2) )
  eti.lower <- quantile(posterior, probs = (1 - interval) / 2)
    
  mean <- mean(posterior)
  median <- median(posterior)
  mode <- (density(as.numeric(posterior))
           $x[which.max(density(as.numeric(posterior))$y)])
  
  hdi.width <- hdi.upper - hdi.lower
  eti.width <- eti.upper - eti.lower
  
  posterior.summary <- 
    tibble(name = name,
           mean = mean,
           median = median,
           mode = mode,
           hdi.lower = hdi.lower,
           hdi.upper = hdi.upper,
           hdi.width = hdi.width,
           eti.lower = eti.lower,
           eti.upper = eti.upper,
           eti.width = eti.width,
           interval = interval)
  
  point.uncertainty <- function(summary, point.estimate = "mean", uncertainty = "hdi") {
    if (point.estimate == "mean" & uncertainty == "hdi")
    {
      paste(sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$mean)), 
            " [", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$hdi.lower)), 
            "-", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$hdi.upper)), 
            "]" , 
            sep = "")
    } else if (point.estimate == "mode" & uncertainty == "hdi")
    {
      paste(sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$mode)), 
            " [", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$hdi.lower)), 
            "-", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$hdi.upper)), 
            "]" , 
            sep = "")
    } else if (point.estimate == "median" & uncertainty == "hdi")
    {
      paste(sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$median)), 
            " [", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$hdi.lower)), 
            "-", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$hdi.upper)), 
            "]" , 
            sep = "")
    } else if (point.estimate == "mean" & uncertainty == "eti")
    {
      paste(sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$mean)), 
            " [", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$eti.lower)), 
            "-", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$eti.upper)), 
            "]" , 
            sep = "")
    } else if (point.estimate == "mode" & uncertainty == "eti")
    {
      paste(sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$mode)), 
            " [", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$eti.lower)), 
            "-", 
            sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$eti.upper)), 
            "]" , 
            sep = "")
    }else if (point.estimate == "median" & uncertainty == "eti")
  {
    paste(sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$median)), 
          " [", 
          sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$eti.lower)), 
          "-", 
          sub("^(-?)0.", "\\1.", sprintf("%.2f", summary$eti.upper)), 
          "]" , 
          sep = "")
  }

  }
  posterior.summary <- posterior.summary %>%
    mutate(label = point.uncertainty(posterior.summary, point.estimate = p.e, uncertainty = u.e))
  
  return(posterior.summary)
}

Review the requested point-estimate and interval-label behavior, including the supplied R example and its supported mean, median, mode, HDI, and ETI combinations. Determine the appropriate bayesplot entry point and API, then define tests or examples that verify the formatting and make clear when the feature is complete.