"https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="st">"T1"</span>,<span class="st">"T2"</span><span class="op">)</span></span>
<span><span class="co"># vector with same items</span></span>
<span><span class="va">itemnr</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/numeric.html" class="external-link">as.numeric</a></span><span class="op">(</span> <span class="fu"><a href="https://rdrr.io/r/base/substr.html" class="e