title: How to plot a dot plot type scatterplot in matplotlib or seaborn?
body: <p>Let's say I have a df like this:</p>
  <pre><code>df = pd.DataFrame({'col1': list('aabbb'), 'col2': [1, 3, 1, 5, 3]})
  
    col1  col2
  0    a     1
  1    a     3
  2    b     1
  3    b     5
  4    b     3
  </code></pre>
  <p>I would like to see a plot, where on the x axis, I have the col1 names ONCE, and on the y axis, the col2 data, as individual dots, so above 'a' I would have two dots at the height of 1 and 3, and above b I would have three dots at the heights of 1, 5 and 3.
  My main problem is that anything I try results in several a and b on the x axis, not grouped.</p>