ath="apply.html"><a href="apply.html"><i class="fa fa-check"></i><b>10</b> 数据聚合与分组运算</a><ul>
<li class="chapter" data-level="10.1" data-path="apply.html"><a href="apply.html#groupby"><i class="fa fa-check"></i><b>10.1</b> GroupBy机制</a></li>
<li class="chapter" data-level="10.2" data-path="apply.html"><a href="apply.html#section-10.2"><i class="fa fa-check"></i><b>10.2</b> 数据聚合</a></li>
<li class="chapter" data-level="10.3" data-path="apply.html"><a href="apply.html#apply"><i cl