擅长:python、mysql、java
<p>您的代码应该简化:</p>
<pre><code>s = (shopdata6['dept']==99).astype(int)
shopdata6['transaction_99'] = s.groupby(shopdata6['id']).cumsum()
print (shopdata6)
id dept date purchase purchase_count_dept99(desired) transaction_99
0 id1 199 date1 $10 0 0
1 id1 99 date1 $10 1 1
2 id1 100 date1 $50 1 1
3 id1 99 date2 $30 2 2
4 id2 100 date1 $10 0 0
5 id2 99 date1 $10 1 1
6 id3 99 date3 $10 1 1
</code></pre>