擅长:python、mysql、java
<p>我不认为如何使用apply,但您可以使用merge:</p>
<pre><code>df['parent_name'] = df[['parent_id']].merge(df[['id', 'name']], left_on=['parent_id'], right_on=['id'], how='left')['name']
# id parent_id name parent_name
# 0 a None Bob NaN
# 1 b None Jane NaN
# 2 c a John Bob
# 3 d b Patty Jane
# 4 e a Sam Bob
</code></pre>