title: Creating boxplot based on three variables
body: <p>How is it possible to create a box plot like <a href="https://i.stack.imgur.com/OilRS.png" rel="nofollow noreferrer">this</a></p>
  <pre><code>data.frame(category = c(2, 3, 3, 3, 2, 2, 3, 3, 3, 3, 2, 3, 1, 3), educational_years = c(6, 15, 16, 6, 6, 6, 12, 12, 12, 4, 12, 15, 6, 4), gender = c(&quot;M&quot;, &quot;F&quot;, &quot;F&quot;, &quot;F&quot;, &quot;M&quot;, &quot;M&quot;, &quot;F&quot;, &quot;M&quot;, &quot;F&quot;, &quot;F&quot;, &quot;M&quot;, &quot;F&quot;, &quot;M&quot;, &quot;F&quot;))
  </code></pre>
  <p>from a data frame like this and x axis have the category y axis age and factor gender</p>