rids.html#spacegrids.abstract.Directional.eq_index">[docs]</a>  <span class="k">def</span> <span class="nf">eq_index</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">collection</span> <span class="p">):</span>
    <span class="sd">&quot;&quot;&quot; Find index of first element in collection equivalent to self under is_equiv.</span>

<span class="sd">    Args:</span>
<span class="sd">      collection: (e.g. List) order collection of Directional objects</span>