title: How to get ggstructure to produce plot in ggplot2
body: <p>I am trying to understand how to use <code>ggstructure</code> in ggplot2. Using the documentation examples, I can successfully get the example code to work: <code>ggstructure(mtcars)</code>. However, I can not get ggstructure to produce any plot from my own data read in from file. For example:</p>
  
  <p>My data looks like this:</p>
  
  <pre><code>colors,hue,saturation,vibrance
  BLUE,10,2,100
  RED,2,86,2
  GREEN,45,23,11
  </code></pre>
  
  <p>My code looks like this:</p>
  
  <pre><code>library(ggplot2)
  data &lt;- read.table("/path/to/data", head=TRUE, sep=",')
  ggstructure(data)
  </code></pre>
  
  <p>When I try to plot with <code>ggstructure</code> I get </p>
  
  <pre><code>Error: Non-continuous variable supplied to scale_fill_gradient2.
  In addition: Warning messages:
  1: In `[&lt;-.factor`(`*tmp*`, ri, value = c(1L, 3L, 2L, NA, NA, NA)) :
  invalid factor level, NAs generated
  2: In `[&lt;-.factor`(`*tmp*`, ri, value = c(1L, 3L, 2L, NA, NA, NA, NA,  :
  invalid factor level, NAs generated
  3: In `[&lt;-.factor`(`*tmp*`, ri, value = c(1L, 3L, 2L, NA, NA, NA, NA,  :
  invalid factor level, NAs generated
  </code></pre>
  
  <p>I also tried to change the data to continuous, but this produced the same problem. Can anyone help? Thanks.</p>