将pandas数据帧转换为键值对列表

Question

I have a pandas dataframe as below:

 col1 col2 
0  a     11
1  b     12
2  b     13
3  a     14
4  a     15 

and I want to convert it into a list which should be like

myList = {'a':['11','14','15'],'b':['12','13']}

Please suggest how to do it?

Answer 1

Group by the first column, collect the values of the second column into lists, convert the result into a dictionary:

df.groupby('col1')['col2'].apply(list).to_dict()
#{'a': ['11', '14', '15'], 'b': ['12', '13']}

Answer 2

Solution from itertools

import itertools

l=df.sort_values('col1').values.tolist()
{k: [x[1] for x in g] for k, g in itertools.groupby(l,lambda x : x[0])}
{'a': [11, 14, 15], 'b': [12, 13]}