n class="op">(</span><span class="va">sample_lf</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span>   subjid agedays lf001 lf002 lf003 lf004 lf005 lf006 lf007 lf008 lf009 lf010</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 1      1     811    NA    NA    NA    NA    NA    NA    NA    NA    NA    NA</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 2      2     898    NA    NA    NA    NA    NA    NA    NA    NA    NA    NA</span>
<