title: R: How can I set the y axis in radians in a plot?
body: <p>I want to plot the arctan of the fractions of two vectors (x and y):</p>
  
  <pre><code>atan.add &lt;- atan(x/y)
  
  plot(atan.add)
  # I get this:
  </code></pre>
  
  <p><img src="https://www.uv.es/balbuena/Rplot.jpeg" alt="artan.plot"></p>
  
  <p>However, is there a way in R to get the y axis numbers as fractions of pi, i.e. pi/2, pi/4, etc.?</p>