擅长:python、mysql、java
<p>您可以使用<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.apply.html" rel="noreferrer">^{<cd1>}</a>:</p>
<pre><code>In [1441]: df['col'] = df.col.str.split('_', expand=True).apply(lambda x: (x[0] + '_' + x[2]) if len(x[2]) == 1 else x[0], axis=1)
In [1442]: df
Out[1442]:
col
0 abcfg
1 abcmn
2 abcgd
3 abcgd_1
</code></pre>