擅长:python、mysql、java
<p>您只需按照预期的格式重新定义列:</p>
<pre><code>import pandas as pd
df = pd.DataFrame({'ID':[1,2,3,4],'postal_code':['k1b6j2','k1b6j3','k1b6j4','k1b6j5']}) ##Example dataset
ID postal_code
0 1 k1b6j2
1 2 k1b6j3
2 3 k1b6j4
3 4 k1b6j5
</code></pre>
<p>按所需格式重新定义<code>postal_code</code>列:</p>
<pre><code>df['postal_code'] = df['postal_code'].astype(str)
df['postal_code'] = [(x[:3]+" "+x[3:]) for x in df['postal_code']]
</code></pre>
<p>输出:</p>
<pre><code> ID postal_code
0 1 k1b 6j2
1 2 k1b 6j3
2 3 k1b 6j4
3 4 k1b 6j5
</code></pre>
<p>最后,与100k长度数据帧中的一些其他方法进行比较:</p>
<pre><code>df['postal_code'] = [(x[:3]+" "+x[3:]) for x in df['postal_code']]
First method time: 0.08260965347290039
df['postal_code'] = df["postal_code"].str[:3] + " " + df["postal_code"].str[3:]
Second method time: 0.112518310546875
</code></pre>