title: Representing negative data on a log scale in Flow Cytometry
body: <p>I'm creating a college app that plots Flow Cytometry data in an XY Graph. It looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/44tzB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/44tzB.png" alt="enter image description here"></a></p>
  
  <p>It works fine for linear plots, but when I need to use logarithmic plots, I cannot represent data that is less than 0 as the log of a negative number is undefined.</p>
  
  <p>So what is the accepted way of representing negative numbers on a log scale in Flow Cytometry? </p>
  
  <p>One option is to add a constant value to all the values so that the smallest value is .001. However, I've seen existing flow cytometry software and it doesnt look like they are using this method (at least to my untrained eye). So what's the generally accepted method to use?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>This is not a duplicate of <a href="https://stackoverflow.com/questions/20924705/plot-negative-values-in-logarithmic-scale-with-ggplot-2">this question</a>. I'm specifically asking what's the accepted way to represent negative numbers on a log scale in Flow Cytometry - not generally how to represent negative numbers on a log scale. The context - Flow Cytometry for blood analysis - is extremely important as its quite subjective, and makes this a different question. </p>
  
  <p><strong>EDIT</strong>
  <a href="http://health.usf.edu/NR/rdonlyres/9869D537-DFC1-458B-B3E7-3356CFF7D08E/27235/interpretingflow.pdf" rel="nofollow noreferrer">This article</a> suggest something called 'logicle' to display negative values. Seems to be a combination of linear and log.</p>