Pandas Groupby: return dict of rows - pandas

Question

I would like to group my dataframe by one of the columns and then return a dictionary that has a list of all of the rows per column value. Is there a fast Pandas idiom for doing this?
Example:
test = pd.DataFrame({
'id': ['alice', 'bob', 'bob', 'charlie'],
'transaction_date': ['2020-01-01', '2020-01-01', '2020-01-02', '2020-01-02'],
'amount': [50.0, 10.0, 12.0, 13.0]
})
Desired output:
result = {
'alice': [Series(transaction_date='2020-01-01', amount=50.0)],
'bob': [Series(transaction_date='2020-01-01', amount=10.0), Series(transaction_date='2020-01-02', amount=12.0)],
'charlie': [Series(transaction_date='2020-01-02', amount=53.0)],
}
The following approaches do NOT work:
test.groupby('id').agg(list)
Returns a Dataframe where each column (amount and transaction_date) has a list of values, but that's not what I want. I want the result to be one list of rows / Pandas series per unique grouping column value ('id' value).
test.groupby('id').agg(list).to_dict():
{'amount': {'charlie': [13.0], 'bob': [10.0, 12.0], 'alice': [50.0]}, 'transaction_date': {'charlie': ['2020-01-02'], 'bob': ['2020-01-01', '2020-01-02'], 'alice': ['2020-01-01']}}
test.groupby('id').apply(list).to_dict():
{'charlie': ['amount', 'id', 'transaction_date'], 'bob': ['amount', 'id', 'transaction_date'], 'alice': ['amount', 'id', 'transaction_date']}

Answer 1

Use itertuples and zip,
import pandas as pd
test = pd.DataFrame({
'id': ['alice', 'bob', 'bob', 'charlie'],
'transaction_date': ['2020-01-01', '2020-01-01', '2020-01-02', '2020-01-02'],
'amount': [50.0, 10.0, 12.0, 13.0]
})
columns = ['transaction_date', 'amount']
grouped = (test
.groupby('id')[columns]
.apply(lambda x: list(x.itertuples(name='Series', index=False))))
print(dict(zip(grouped.index, grouped.values)))
{
'alice': [Series(transaction_date='2020-01-01', amount=50.0)],
'bob': [
Series(transaction_date='2020-01-01', amount=10.0),
Series(transaction_date='2020-01-02', amount=12.0)
],
'charlie': [Series(transaction_date='2020-01-02', amount=13.0)]
}