title: heatmap without ordering and dendrogram
body: <p>I have a file with 2 columns and 1 million lines!! I only want to plot them without any ordering because I ordered the data.   How can I make a heatmap with heatmap.2 without any dendrogram and reordering?</p>
  
  <p>when I use  </p>
  
  <pre><code>heatmap.2(x, dendrogram="none")
  
  Error: cannot allocate vector of size 4660.6 Gb
  </code></pre>
  
  <p>but </p>
  
  <p>I tried without <code>"Rowv"</code> </p>
  
  <pre><code>heatmap.2(x, Rowv=FALSE) 
  
  Warning message:
  In heatmap.2(x, Rowv = FALSE) :
    Discrepancy: Rowv is FALSE, while dendrogram is `column'. Omitting row dendogram.
  </code></pre>