以o2o大赛的数据为例

df_new = df[[‘User_id’,’Merchant_id’]]

df_new_1 = df_new.groupby([‘User_id’])[‘Merchant_id’].nunique()

在同一个’User_id’下，’Merchant_id’有多少个

df_new_1 = df_new.groupby([‘User_id’])[‘Merchant_id’].value_counts()

Name: Merchant_id, dtype: int64

df_new_1 = df_new.groupby([‘User_id’])[‘Merchant_id’].unique()

返回具体的unique值

Series.nunique(dropna=True)[source]

Return number of unique elements in the object.

Excludes NA values by default

源码
def

nunique
(
self
,
dropna
=
True
):
“””
Return number of unique elements in the object.
Excludes NA values by default.
Parameters
———-
dropna : boolean, default True
Don’t include NaN in the count.

Returns
——-
nunique : int
“””
uniqs
=

self
.unique()
n
=

len
(uniqs)
if
dropna
and
isna(uniqs).any():
n
-=

1
return
n

.