使用多个值从熊猫系列创建字典

Question

I have a pd dataframe as follow:

df=pd.DataFrame([['A',1],['A',3],['B',2],['B',5],['C',8]],columns=['k','v'])

And from I would like to create the following dictionary:

{'A':[1,3],
 'B':[2,5],
 'C':[8]
}

I am currently doing it with:

from collections import defaultdict


my_dict=defaultdict(list)

for key in df.k:
    my_dict[key].append(df['v'][df['k']==key])

But it is not efficient (very time consuming) for large df and also sends me back the index of the values, which I do not want.

Any suggestions?

Thanks

Answer 1

你可以在这里使用agg ：

df.groupby('k').v.agg(list).to_dict()

{'A': [1, 3], 'B': [2, 5], 'C': [8]}