擅长:python、mysql、java
<p>似乎您需要<a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.groupby.html" rel="nofollow noreferrer">^{<cd1>}</a>和聚合<code>sum</code>,最后由<code>unstack</code>整形:</p>
<pre><code>df = df.groupby(['Year', 'LoanType'])['loan notional'].sum().unstack()
</code></pre>