擅长:python、mysql、java
<p>一种方法是使用<a href="https://numpy.org/doc/stable/reference/generated/numpy.select.html" rel="nofollow noreferrer">^{<cd1>}</a>并将结果用作grouper:</p>
<pre><code>import numpy as np
southern=['spain', 'greece', 'italy']
northern=['belgium','germany']
g = np.select([df.name.isin(southern),
df.name.isin(northern)],
['southern', 'northern'],
'others')
df.groupby(g).sum()
davalue
northern 15
southern 10
</code></pre>