title: Filter row names based on string length
body: <p>I want to filter rows that contain rownames longer than 35  and shorter than 10. 
  I was looking at the <code>nchar</code> function. </p>
  
  <pre><code>                                    79_CGTACG.collapsed.gz 80_ACAGTG.collapsed.gz
  CACCCGCACGTATAGACGGACA                                   0                      0
  GTGCTGATGTCCTTGGCAGGCTTCGGCCGTCCGGC                      0                      0
  CGTGGAACCTG                                              0                      0
  TAATGGTCATTAG                                            2                      1
  GGCGATGCGGGATGAACCGAAC                                   0                      0
  AAGGATGT                                                 0                      0
  </code></pre>