title: How to create facet heatmap ggplot2
body: <p>I have a load of genomic data as follows:</p>
  
  <pre><code>chr   leftPos   Sample1    AnotherSample  EtcSample
  1     4324       434          43           33
  1     5353       63           34           532
  1     6632       543          3544         23
  2     1443       25           345          543
  2     7644       74           26           324
  2     8886       23           9            23
  3     1287       643          45           23
  3     5443       93           23           77
  3     7668       33           45           33
  </code></pre>
  
  <p>I would like to create a heatmap organised by chromosome with sample along the x-axis and leftPos along the Y axis. I think this would look good in a facet_wrap image (organised by chromosome) but this means I have to use heatmaps in ggplots and I understand this isn't a thing so I have to use geom_tiles().</p>
  
  <p>So I tried googling all over the place but I'm stuck with how to firstly do a heatmap per chromosome and secondly do tiles per sample. All the examples seem to just use two columns.</p>