Originally posted by **augcollet** November 13, 2024
Hello,
I need your help to resolve a specific problem...
From the following data with postgresql backend :
```python
import ibis
from ibis import _
import os
con = ibis.postgres.connect(
user=os.getenv('POSTGRES_USER'),
password=os.getenv('POSTGRES_PASSWORD'),
host="postgres",
port=os.getenv('POSTGRES_PORT'),
database=os.getenv('POSTGRES_DB'),
)
ibis.set_backend(con)
t=ibis.memtable({
'client_id':[0,1,0,2,3,0,1,2,3],
'product':['a', 'b', 'a', 'a', 'b', 'c', 'a', 'a', 'b'],
'amount':[1.2, 2.5, 4.2, 12.7, 1.2, 3.8, 1.4, 3.8, 3],
})
```
I'm trying to perform the following calculation :
I tried the following approach:
```python
data=(
t.group_by(['client_id', 'product'])
.agg(
sum_amount=_['amount'].sum()
)
.group_by(['client_id'])
.agg(
products_and_sum_amounts=ibis.map(
_['product'].collect(),
_['sum_amount'].collect()
)
)
)
data.execute()
```
I get the following error :
It seems that ibis uses hstore to store data from a .map, which is incompatible with numeric values.
I have to cast the values to a string before using .collect to get a result.
How can I get around this? For example, how can I build a JSON object instead of MapValue?
( My goal is to exploit the resulting pandas dataset to use it with a DictVectorizer under sklearn.
https://scikit-learn.org/1.5/modules/generated/sklearn.feature_extraction.DictVectorizer.html )
Thank you in advance for your support!
Discussed in https://github.com/ibis-project/ibis/discussions/10483