title: Creating heatmap displaying gene expression using image() function
body: <p>I have received codes from other lab using the following line:</p>
  
  <pre class="lang-r prettyprint-override"><code>image(plot_bm.mat, col = mycol, axes = F, useRaster = T, zlim = c(z.lim[1], z.lim[2]))
  </code></pre>
  
  <p>in which <code>mycol &lt;- colItay(seq(0,1,0.01))[30:100]</code>.</p>
  
  <p>The resulting image is </p>
  
  <p><img src="https://i.stack.imgur.com/gz1yr.png" alt="this"></p>
  
  <p>I cannot find the function <code>colItay</code>. Could someone please explain to me what this is?</p>