title: ggplot2() bar chart fill argument
body: <p>I've got a data frame with two categorical variables called verified and procedure. </p>
  
  <p>I'd like to make a bar chart with procedure on the x-axis, and the corresponding percentages rather than counts on the y-axis. Furthermore, I'd like for verified to be the fill of the bars. </p>
  
  <p>The problem's that when I've tried using the fill argument it hasn't worked. My current code gets me bars that are all grey with a black line (despite the absence of a fill argument the black line seems to indicate the levels of verified???). Instead I'd like the levels to be in different colours. </p>
  
  <p>Thanks!   </p>
  
  <p>starting point (df):</p>
  
  <pre><code>df &lt;- data.frame(verified=c("small","large","small","small","large","small","small","large","small"),procedure=c(1,2,1,2,1,2,2,2,2)) 
  </code></pre>
  
  <p>current code:</p>
  
  <pre><code>library(dplyr)
  library(gglot2)
  df  %&gt;%
    count(procedure,verified) %&gt;%
    mutate(prop = round((n / sum(n))*100),2)  %&gt;%
    group_by(procedure)  %&gt;% 
      ggplot(aes(x = procedure, y = prop)) +
      geom_bar(stat = "identity",colour="black") 
  </code></pre>