擅长:python、mysql、java
<p>为<code>Age</code>列添加括号和<code>loc</code>:</p>
<pre><code>m = train.loc[(train['Age'] > 15) & (train['Age'] < 45), 'Age'].mean()
</code></pre>
<p>或者使用<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.between.html" rel="nofollow noreferrer">^{<cd3>}</a>:</p>
<pre><code>m = train.loc[train['Age'].between(15, 45, inclusive=False), 'Age'].mean()
</code></pre>
<p>最后替换缺少的值:</p>
<pre><code>train['Age'] = train['Age'].fillna(m)
</code></pre>