擅长:python、mysql、java
<p>在我看来,您需要按<code>id</code>分组并计数,然后将其作为键在新列中执行操作。你知道吗</p>
<pre><code>counts = test.groupby("id").count()
test["score/id.size"] = test.apply(lambda x: x["score"] / float(counts[counts.index==x["id"]].score), axis=1)
test
id score score/id.size
4 1 0.875933 0.291978
5 1 0.357817 0.119272
6 1 0.500995 0.166998
3 2 0.958139 0.319380
7 2 0.683463 0.227821
9 2 0.370251 0.123417
2 3 0.801872 0.801872
0 4 0.272593 0.090864
1 4 0.276464 0.092155
8 4 0.712702 0.237567
</code></pre>