dv">2</span> &lt;-<span class="st"> </span><span class="kw">data.table</span>(<span class="dt">X =</span> <span class="kw">c</span>(<span class="dv">10</span>, <span class="dv">10</span>, <span class="dv">30</span>, <span class="dv">30</span>, <span class="dv">50</span>, <span class="dv">50</span>, <span class="dv">70</span>, <span class="dv">70</span>, <span class="dv">90</span>, <span class="dv">90</span>), <span class="dt">Y =</span> <span class="kw">c</span>(<span class="dv">25</span>, <span class="dv">