擅长:python、mysql、java
<p>使用由<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.set_index.html" rel="nofollow noreferrer">^{<cd3>}</a>创建的<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.map.html" rel="nofollow noreferrer">^{<cd1>}</a>by <code>Series</code>,如果某些值不匹配,则用<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.fillna.html" rel="nofollow noreferrer">^{<cd4>}</a>替换:</p>
<pre><code>s = df['col1'].map(df_reference.set_index('col1')['col2']).fillna(df['col2'])
df.loc[s > df['col2'], 'col2'] = s
print (df)
col1 col2
0 A 15
1 B 33
2 C 30
3 A 15
</code></pre>