How to convert pandas dataframe to hierarchical dictionary

Question

I have the following pandas dataframe:

df1 = pd.DataFrame({'date': [200101,200101,200101,200101,200102,200102,200102,200102],'blockcount': [1,1,2,2,1,1,2,2],'reactiontime': [350,400,200,250,100,300,450,400]})

I am trying to create a hierarchical dictionary, with the values of the embedded dictionary as lists, that looks like this:

{200101: {1:[350, 400], 2:[200, 250]}, 200102: {1:[100, 300], 2:[450, 400]}}

How would I do this? The closest I get is using this code:

df1.set_index('date').groupby(level='date').apply(lambda x: x.set_index('blockcount').squeeze().to_dict()).to_dict()

Which returns:

{200101: {1: 400, 2: 250}, 200102: {1: 300, 2: 400}}

Answer 1

Here is another way using pivot_table:

d = df1.pivot_table(index='blockcount',columns='date',
     values='reactiontime',aggfunc=list).to_dict()

---

print(d)

{200101: {1: [350, 400], 2: [200, 250]},
 200102: {1: [100, 300], 2: [450, 400]}}