out co"><span class="r-pr">#&gt;</span>  $ BC.Age   : int  1 2 3 4 1 2 1 2 3 4 ...</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ BC.Len   : num  99.4 205.2 319.8 390.4 135.5 ...</span>
<span class="r-in"><span><span class="fu"><a href="https://rdrr.io/r/utils/head.html" class="external-link">head</a></span><span class="op">(</span><span class="va">WalleyeML</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span>             ID Year Sex Est.Age 