title: How to use R ggplot stat_summary to plot median and quartiles?
body: <p>how to change the lower and upper point in this stat summary plot to 25% quartile and 75% quartile?</p>
  <pre><code>ggplot(data = diamonds) + stat_summary(
    mapping = aes(x = cut, y = depth),
    fun.ymin = min,
    fun.ymax = max,
    fun.y = median
  )
  </code></pre>