擅长:python、mysql、java
<p>只是使用unstack()的另一种方法:</p>
<pre><code>df=df.groupby(['user', 'day']).sum().unstack('day') #unstack
df.columns = df.columns.droplevel() # drop first level column name
df
</code></pre>
<p>输出:</p>
<pre><code>day Mon Tue Wed
user
U1 15.0 NaN 15.0
U2 7.0 25.0 NaN
U3 NaN 21.0 NaN
</code></pre>