Python Dataframe 元素组合问题

Question

我现在有一个Dataframe

df = pd.DataFrame({'a':['A','A','A','A','B','B','B','C','C','C','D','D'],
'b':['a','b','c','d','a','b','c','a','b','c','a','d']}

我想要做到基于A列的，B列的元素两两组合
得到如下结果

Answer 1

借助于itertools中的combination函数，获取a,b,c,d两两组合。然后转换一下就可以了。

import pandas as pd
from itertools import combinations
df = pd.DataFrame({'a':['A','A','A','A','B','B','B','C','C','C','D','D'],
'b':['a','b','c','d','a','b','c','a','b','c','a','d']})
a=list(combinations(['a','b','c','d'],2))*2
df.b=[x[0]+','+x[1] for x in a]
print(df)