擅长:python、mysql、java
<p>对每个组使用<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.value_counts.html" rel="nofollow noreferrer">^{<cd1>}</a>字典理解:</p>
<pre><code>d = {k: v.value_counts(sort=False).to_dict()
for k, v in df.groupby('country', sort=False)['operations']}
print (d)
{'India': {'A': 1, 'C': 2}, 'Malaysia': {'B': 1, 'A': 1, 'D': 1}, 'Croatia': {'C': 1}}
</code></pre>