迭代df并输出带有值列表的字典

Question

I need to convert a dataframe to a dictionary but can't get all of the values from the dataframe to appear within the dictionary.

dataframe:

id| region | Num | 
--|--------|-----|
2 | NYC    |2344 |
3 | NYC    |3243 |
4 | NYC    |3253 |
5 | NYC    |2345 |
6 | CHI    |8756 |
7 | CHI    |9786 |
8 | CHI    |7674 |
9 | CHI    |6678 |
10| ATL    |1234 |

code:

df.set_index('region').T.to_dict('list') :

What I need is this:

{'NYC: [2344, 3243, 3253, 2345 ], 'CHI': [8756, 9786, 7674, 6678], 'ATL': [1234] }

but what I'm getting is this:

{'NYC: [2345 ], 'CHI': [6678], 'ATL': [1234] }

I tried:

    num_dict = {}
    for region, num in df:
        num_dict.setdefault(region, []).append(num)

But this gives me a (ValueError: too many values to unpack (expected 2) .

Is there a better way to do this?

Thanks in advance!

Answer 1

Use groupby.apply(list) then .to_dict

df.groupby('region')['Num'].apply(list).to_dict()

[out]

{'ATL': [1234],
 'CHI': [8756, 9786, 7674, 6678],
 'NYC': [2344, 3243, 3253, 2345]}