r">#&gt;</span> r=41	r=42	r=43	r=44	r=45	</span>
<span class="r-in"><span><span class="fu">plot_mt</span><span class="op">(</span><span class="va">res</span><span class="op">)</span></span></span>
<span class="r-wrn co"><span class="r-pr">#&gt;</span> <span class="warning">Warning: </span>invalid factor level, NA generated</span>
<span class="r-plt img"><img src="plot_mt-1.png" alt="" width="700" height="433"></span>
<span class="r-in"><span><span class="fu">plot_mt</span><span class="op">(</span><span clas