擅长:python、mysql、java
<p>另一种选择是<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.groupby.html" rel="nofollow noreferrer">^{<cd1>}</a>这个<code>datesurv</code>,也可以使用<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Grouper.html" rel="nofollow noreferrer">^{<cd3>}</a>来创建6个月的组,并使用<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.core.groupby.GroupBy.cumcount.html" rel="nofollow noreferrer">^{<cd4>}</a>:</p>
<pre><code>df.datesurv = pd.to_datetime(df.datesurv, format='%d/%m/%Y')
g = pd.Grouper(key='datesurv', freq='6MS')
df.assign(occ=df.groupby(['id_police', g]).cumcount())
id_police id_sinistre datesurv occ
0 p123 s120 2018-01-01 0
1 p123 s121 2018-01-03 1
2 p123 s122 2018-05-05 2
3 p222 s123 2018-05-04 0
4 p222 s124 2018-12-02 0
5 p433 s125 2018-08-07 0
6 p433 s126 2018-09-08 1
7 p433 s127 2018-10-10 2
</code></pre>