 class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="st">'a'</span> <span class="op">=</span> <span class="st">'b'</span>, <span class="st">'d'</span> <span class="op">=</span> <span class="cn">NA</span>, <span class="st">'e'</span> <span class="op">=</span> <span class="st">'f'</span><span class="op">)</span><span class="op">)</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> c('a' = 'b