擅长:python、mysql、java
<p>按<code>Series</code>使用双<a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.map.html" rel="nofollow noreferrer">^{<cd1>}</a>:</p>
<pre><code>s = df2.set_index('ID')['name']
df1['name1'] = df1['ID1'].map(s)
df1['name2'] = df1['ID2'].map(s)
</code></pre>
<p>备选方案:</p>
<pre><code>df1 = df1.assign(name1=df1['ID1'].map(s), name2=df1['ID2'].map(s))
</code></pre>
<hr/>
<pre><code>print (df1)
df1 ID1 ID2 name1 name2
0 0 0 2 John Eva
1 1 1 3 Carl Julia
2 2 3 2 Julia Eva
3 3 1 2 Carl Eva
</code></pre>