擅长:python、mysql、java
<h3><a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.str.zfill.html" rel="nofollow noreferrer">^{<cd1>}</a></h3>
<pre><code>df = df.astype(str) # Making sure these are strings
mask = df.numbers.str.len() == 4
df.loc[mask, 'numbers'] = df.loc[mask, 'numbers'].str.zfill(5)
df
numbers
0 111
1 22222
2 03423
</code></pre>