/rdrr.io/r/base/NA.html" class="external-link">is.na</a></span><span class="op">(</span><span class="va">Tn_mes</span><span class="op">[</span>,<span class="va">it</span><span class="op">]</span><span class="op">)</span><span class="op">)</span><span class="op">)</span><span class="op">==</span><span class="fu"><a href="https://rdrr.io/r/base/length.html" class="external-link">length</a></span><span class="op">(</span><span class="va">Tn_mes</span><span class="op">[</span>,<span class="va">it</span><span cl