擅长:python、mysql、java
<p>使用<code>apply</code>:</p>
<pre><code>mask = ~df['col_list'].isna()
df.loc[mask , 'col_list'] = df.loc[mask, 'col_list'].apply(lambda x: ', '.join(x))
#or
df.loc[mask, 'col_list'] = [','.join(elems) for elems in df.loc[mask, 'col_list']]
</code></pre>