擅长:python、mysql、java
<p>您需要将<a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.transform.html" rel="nofollow noreferrer">transform</a>与<code>'count'</code>一起使用。你知道吗</p>
<pre><code>train_data['NumberOfSegment'] = train_data.groupby('CtpJobId')['SegmentId'].transform('count')
</code></pre>
<p>输出:</p>
<pre><code> CtpJobId SegmentId NumberOfSegment
0 qa1-9epx-dk1 347772 1
1 qa1-9epx-dv1 347774 7
2 qa1-9epx-dv1 347777 7
3 qa1-9epx-dv1 347780 7
4 qa1-9epx-dv1 347783 7
5 qa1-9epx-dv1 347786 7
6 qa1-9epx-dv1 347789 7
7 qa1-9epx-dv1 347792 7
8 qa1-9epx-e01 347794 1
9 qa1-9epx-eb2 347795 1
10 qa1-9epx-ez1 347796 1
11 qa1-9epx-f32 347797 1
12 qa1-9epx-fi1 347798 1
</code></pre>