"></i><b>7.2</b> 数据转换</a></li>
<li class="chapter" data-level="7.3" data-path="tidy.html"><a href="tidy.html#section-7.3"><i class="fa fa-check"></i><b>7.3</b> 字符串操作</a></li>
<li class="chapter" data-level="7.4" data-path="tidy.html"><a href="tidy.html#-4"><i class="fa fa-check"></i><b>7.4</b> 总结</a></li>
</ul></li>
<li class="chapter" data-level="8" data-path="reshape.html"><a href="reshape.html"><i class="fa fa-check"></i><b>8</b> 数据规整：聚合、合并和重塑</a><ul>
<li c