fix d1 of item O28 to -0.5</span></span>
<span><span class="va">ind</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/which.html" class="external-link">which</a></span><span class="op">(</span> <span class="op">(</span> <span class="va">mirt.pars</span><span class="op">$</span><span class="va">item</span><span class="op">==</span><span class="st">"O28"</span> <span class="op">)</span> <span class="op">&amp;</span> <span class="op">(</span> <span class="va">mirt.pars</span