<p>使用从<code>df1</code>和<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.fillna.html" rel="nofollow noreferrer">^{<cd4>}</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>替换不匹配的值:</p>
<pre><code>print (df2)
Survived Surname FamilySize NumSurvived
0 0 Braund 2 0
1 1 Cumings1 1 1 <- change surname for no match
2 1 Heikkinen 1 1
3 1 Futrelle 2 1
4 0 Allen 2 1
5 0 Moran 3 1
6 0 McCarthy 1 0
7 0 Palsson 4 0
s = df1.set_index('Surname')['FamilySurvivalRate']
df2['FamilySurvivalRate'] = df2['Surname'].map(s).fillna(0)
print (df2)
Survived Surname FamilySize NumSurvived FamilySurvivalRate
0 0 Braund 2 0 0.000000
1 1 Cumings1 1 1 0.000000
2 1 Heikkinen 1 1 1.000000
3 1 Futrelle 2 1 0.500000
4 0 Allen 2 1 0.500000
5 0 Moran 3 1 0.333333
6 0 McCarthy 1 0 0.000000
7 0 Palsson 4 0 0.000000
</code></pre>