sql选择组由python pandas中的count(1)> 1等效？

我很难过滤pandas中的groupby项目.我想要做

select email, count(1) as cnt 
from customers 
group by email 
having count(email) > 1 
order by cnt desc

我做到了

customers.groupby('Email')['CustomerID'].size()

它正确地给了我电子邮件列表及其各自的计数,但我无法实现计数(电子邮件)> 1部分.

email_cnt[email_cnt.size > 1]

返回1

email_cnt = customers.groupby('Email')
email_dup = email_cnt.filter(lambda x:len(x) > 2)

通过电子邮件给出客户的整个记录​​> 1但我想要聚合表.

解决方法:

而不是写email_cnt [email_cnt.size> 1],只需写下email_cnt [email_cnt> 1](没有必要再次调用.size).这使用布尔系列email_cnt> 1只返回email_cnt的相关值.

例如：

>>> customers = pd.DataFrame({'Email':['foo','bar','foo','foo','baz','bar'],
                              'CustomerID':[1,2,1,2,1,1]})
>>> email_cnt = customers.groupby('Email')['CustomerID'].size()
>>> email_cnt[email_cnt > 1]
Email
bar      2
foo      3
dtype: int64