title: How to put black borders in heatmap in R
body: <p>Hi
  I created a heatmap in R using "heatmap.plus" which is shown in the link </p>
  
  <p><a href="http://i.stack.imgur.com/hizBf.jpg">http://i.stack.imgur.com/hizBf.jpg</a></p>
  
  <p>but I need the heat map to look like the heatmap shown in below link which was created from some other GUI software</p>
  
  <p><a href="http://i.stack.imgur.com/Y8Faj.png">http://i.stack.imgur.com/Y8Faj.png</a></p>
  
  <p>How can I put black borders in every heatmap element in R</p>