title: How to control number of decimal digits in write.table() output?
body: <p>When working with data (e.g., in data.frame) the user can control displaying digits by using</p>
  
  <pre><code>options(digits=3) 
  </code></pre>
  
  <p>and listing the data.frame like this.</p>
  
  <pre><code>ttf.all
  </code></pre>
  
  <p>When the user needs to paste the data in Excell like this</p>
  
  <pre><code>write.table(ttf.all, 'clipboard', sep='\t',row.names=F)
  </code></pre>
  
  <p>The digits parameter is ignored and numbers are not rounded.</p>
  
  <p>See nice output</p>
  
  <pre><code>&gt; ttf.all
    year V1.x.x V1.y.x ratio1 V1.x.y V1.y.y ratioR V1.x.x V1.y.x ratioAL V1.x.y V1.y.y ratioRL
  1 2006    227    645   35.2     67    645   10.4    150    645    23.3     53    645    8.22
  2 2007    639   1645   38.8    292   1645   17.8    384   1645    23.3    137   1645    8.33
  3 2008   1531   3150   48.6    982   3150   31.2    755   3150    24.0    235   3150    7.46
  4 2009   1625   3467   46.9   1026   3467   29.6    779   3467    22.5    222   3467    6.40
  </code></pre>
  
  <p>But what is in excel (clipboard) is not rounded. How to control in in <code>write.table()</code>?</p>