title: R plot() - why do my points appear as horizontal lines
body: <p>I'm trying to make a plot in R. My x-axis is a week number converted to factor and my y-axis is an amount.<br>
  When I run <code>plot()</code> instead of dots I get horizontal lines.<br>
  Why does this happen?<br>
  Here is a sample dataset:</p>
  
  <pre><code>df &lt;- data.frame(fin_week=as.factor(seq(1,20, by =1)), amount=(rnorm(20)^2)*100)
  plot(df)
  </code></pre>