title: R ggplot2: Why do I get the error "Error in f(..., self = self) : attempt to apply non-function"?
body: <p>I was trying to test out the <a href="https://github.com/eclarke/ggbeeswarm" rel="nofollow noreferrer"><code>ggbeeswarm</code></a> package.</p>
  
  <p>Unfortunately, I get an error when I run the commands below.
  Why do I get this error?</p>
  
  <pre><code>R version 3.2.4 Revised (2016-03-16 r70336) -- "Very Secure Dishes"
  Copyright (C) 2016 The R Foundation for Statistical Computing
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  
  R is free software and comes with ABSOLUTELY NO WARRANTY.
  You are welcome to redistribute it under certain conditions.
  Type 'license()' or 'licence()' for distribution details.
  
  R is a collaborative project with many contributors.
  Type 'contributors()' for more information and
  'citation()' on how to cite R or R packages in publications.
  
  Type 'demo()' for some demos, 'help()' for on-line help, or
  'help.start()' for an HTML browser interface to help.
  Type 'q()' to quit R.
  
  &gt; require(ggbeeswarm)
  Loading required package: ggbeeswarm
  Loading required package: ggplot2
  Warning messages:
  1: package ‘ggbeeswarm’ was built under R version 3.2.5 
  2: package ‘ggplot2’ was built under R version 3.2.5 
  &gt; ggplot(iris,aes(Species, Sepal.Length)) + geom_quasirandom()
  Error in f(..., self = self) : attempt to apply non-function
  </code></pre>