 class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">_sparse</span><span class="p">:</span>
                <span class="n">sample_offset</span> <span class="o">=</span> <span class="mi">0</span>
                <span class="n">data</span> <span class="o">=</span> <span class="p">[]</span>
                <span class="n">coords</span> <span class="o">=</span> <span class="p">[]</span>
                <span class="k">for</span> <span class="n">i</span><span class="p">,</sp