擅长:python、mysql、java
<ul>
<li>生成月开始日期和<code>reindex</code></li>
<li><code>ffill</code>和<code>bfill</code>列<code>['email', 'user_name']</code></li>
<li><code>fillna(0)</code>列<code>'sessions'</code></li>
</ul>
<hr/>
<pre><code>mbeg = pd.date_range('2015-01-31', periods=12, freq='M') - pd.offsets.MonthBegin()
df1 = df.set_index('ymo').reindex(mbeg)
df1[['email', 'user_name']] = df1[['email', 'user_name']].ffill().bfill()
df1['sessions'] = df1['sessions'].fillna(0).astype(int)
df1
</code></pre>
<p><a href="https://i.stack.imgur.com/FHOKR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FHOKR.png" alt="enter image description here"/></a></p>