text: user4595: I have this dataframe 
  > head(mut)
    sample chr     pos ref alt
  1  t_005   1  928006   G   A
  2  t_005   1 1649842   G   T
  3  t_005   1 2020408   G   A
  4  t_005   1 2031677   T   A
  5  t_005   1 2901878   G   A
  6  t_005   1 3039338   G   A
  >
  
  How I can add "chr" to the chr column? I mean, instead of "1" I want "chr1", etc.
  
  user4001: This should work:
  mut$chr <- paste("chr", mut$chr, sep = "")
  
  
original_text: 4595: <p>I have this dataframe </p>
  
  <pre><code>&gt; head(mut)
    sample chr     pos ref alt
  1  t_005   1  928006   G   A
  2  t_005   1 1649842   G   T
  3  t_005   1 2020408   G   A
  4  t_005   1 2031677   T   A
  5  t_005   1 2901878   G   A
  6  t_005   1 3039338   G   A
  &gt;
  </code></pre>
  
  <p>How I can add <code>"chr"</code> to the <code>chr</code> column? I mean, instead of <code>"1"</code> I want <code>"chr1"</code>, etc.</p>
   4001: <p>This should work:</p>
  
  <pre><code>mut<span class="math-container">$chr &lt;- paste("chr", mut$</span>chr, sep = "")
  </code></pre>
  