.data.frame</a></span><span class="op">(</span><span class="op">)</span>
<span class="va">ex_3</span><span class="op">$</span><span class="va">ROWSUM</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/colSums.html" class="external-link">rowSums</a></span><span class="op">(</span><span class="va">ex_3</span><span class="op">)</span>

<span class="co">## Print</span>
<span class="fu"><a href="https://rdrr.io/r/base/print.html" class="external-link">print</a></span><span clas