n class="n">grid_data</span><span class="p">[</span><span class="s1">&#39;precip&#39;</span><span class="p">]</span><span class="o">.</span><span class="n">isnull</span><span class="p">()</span><span class="o">.</span><span class="n">sum</span><span class="p">()</span>

<span class="gp">In [25]: </span><span class="k">assert</span> <span class="p">(</span><span class="n">nan1</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="p">)</span> <span class="o">&amp;</span> <span class="p">(