擅长:python、mysql、java
<p>您可以使用<a href="https://pandas.pydata.org/pandas-docs/version/0.23.4/generated/pandas.crosstab.html" rel="nofollow noreferrer">crosstab</a>:</p>
<pre><code>import pandas as pd
a = pd.DataFrame(
{'trn_id': [1, 2, 3, 4, 5],
'card_id': ['c1', 'c2', 'c2', 'c3', 'c3'],
'status': ['Y', 'Y', 'N', 'Y', 'Y']})
crosstab = pd.crosstab(a.card_id, a.status).reset_index(level=0).rename(
columns={'Y': 'num_approved', 'N': 'num_denied'})
print(pd.merge(a, crosstab, on='card_id'))
</code></pre>
<p><strong>输出</strong></p>
<pre><code> card_id status trn_id num_denied num_approved
0 c1 Y 1 0 1
1 c2 Y 2 1 1
2 c2 N 3 1 1
3 c3 Y 4 0 2
4 c3 Y 5 0 2
</code></pre>