title: Circadian Phase plot in R
body: <p>I've seen a figure in a paper (Perales &amp; Mas, 2007; Plant Cell) and I'm interested in making a similar graph with my data in R.</p>
  
  <p>I have some circadian gene expression data and I need to represent which is the phase (the maximum peak of expression of a certain gene) of some genes. The graph I'm refering to is like a clock in which you can see at what time a gene has its maximum peak of expression.</p>
  
  <p><img src="https://i.stack.imgur.com/NTqO2.png" alt="Perales-Mas-2007-Plant-Cell-figure-5c"></p>
  
  <blockquote>
    <p>(C) Phase plot of TOC1:LUC and CAB2:LUC expression in wild-type and TMG plants under the indicated photoperiods. Phases (phase/period × 24 h) were plotted against the strength of the rhythm expressed as relative amplitude error. The rhythm strength is graphed from 0 (center of the plot) to 0.8 (periphery of the circle), which indicates robust and very weak rhythms, respectively.</p>
  </blockquote>