title: reduce width of columns on a heatmap.2 plot
body: <p>I have a 331*9 double matrix (named expr001). It looks like this:</p>
  
  <pre><code>row.names     Col1      Col2      Col3      Col4      Col5      Col6    Col7       Col8      Col9
  17211382  7.397439  7.377975  7.299997  8.192889  8.292300  8.092921  8.178948  8.120986  8.276824
  17211752  9.115307  9.116741  9.113366  8.423073  8.458392  8.573309  8.773752  8.614159  8.592105
  17212229  5.968911  6.060437  6.059898  5.595364  5.471327  5.538794  5.584753  5.518935  5.498830
  17215629  8.641765  8.810358  8.770533  7.482992  7.732727  7.811839  8.582255  8.404402  8.357516
  17215820 11.495858 11.605611 11.529879 11.124909 11.107311 11.179045 11.165894 11.188668 11.210991
  </code></pre>
  
  <p>And I am generating a heatmap using heatmap.2 </p>
  
  <pre><code>heatmap.2(expr001,main="\n331 Genes : P.adj&lt;0.01",cexCol=0.9,tracecol=NULL,col="bluered")
  </code></pre>
  
  <p>I get the plot below:</p>
  
  <p><img src="https://i.stack.imgur.com/YaebN.png" alt="enter image description here"></p>
  
  <p>How can I reduce the width of the columns? Any suggestions?</p>