Aggregate rows does not work without group key

[simonaubertbd]

Hello,

Aggregate rows does not work if we don't specify a group key (i.e. if we want to aggregate on all rows)

`Error

No group keys passed!
Show Traceback

---

ValueError Traceback (most recent call last)
Cell In[24], line 8
3 # Source code generated by Amphi
4 # Date: 2024-12-05 08:55:32
5 # Additional dependencies: pyarrow
6 import pandas as pd
----> 8 aggregate1 = parquetFileInput1.groupby([]).agg(c_phone_min=('c_phone', 'min')).reset_index()
11 __amphi_display_dataframe(aggregate1, dfName="aggregate1", nodeId="node_1733386206267")

File ~\AppData\Local\Programs\Python\Python312\Lib\site-packages\pandas\core\frame.py:9170, in DataFrame.groupby(self, by, axis, level, as_index, sort, group_keys, observed, dropna)
9167 if level is None and by is None:
9168 raise TypeError("You have to supply one of 'by' and 'level'")
-> 9170 return DataFrameGroupBy(
9171 obj=self,
9172 keys=by,
9173 axis=axis,
9174 level=level,
9175 as_index=as_index,
9176 sort=sort,
9177 group_keys=group_keys,
9178 observed=observed,
9179 dropna=dropna,
9180 )

File ~\AppData\Local\Programs\Python\Python312\Lib\site-packages\pandas\core\groupby\groupby.py:1329, in GroupBy.init(self, obj, keys, axis, level, grouper, exclusions, selection, as_index, sort, group_keys, observed, dropna)
1326 self.dropna = dropna
1328 if grouper is None:
-> 1329 grouper, exclusions, obj = get_grouper(
1330 obj,
1331 keys,
1332 axis=axis,
1333 level=level,
1334 sort=sort,
1335 observed=False if observed is lib.no_default else observed,
1336 dropna=self.dropna,
1337 )
1339 if observed is lib.no_default:
1340 if any(ping._passed_categorical for ping in grouper.groupings):

File ~\AppData\Local\Programs\Python\Python312\Lib\site-packages\pandas\core\groupby\grouper.py:1071, in get_grouper(obj, key, axis, level, sort, observed, validate, dropna)
1068 groupings.append(ping)
1070 if len(groupings) == 0 and len(obj):
-> 1071 raise ValueError("No group keys passed!")
1072 if len(groupings) == 0:
1073 groupings.append(Grouping(Index([], dtype="int"), np.array([], dtype=np.intp)))

ValueError: No group keys passed!`

[tgourdel]

Hi Simon, not sure how that works. If you don't select any columns to group by, how should it aggregate your rows?

[simonaubertbd]

@tgourdel like that :

input

Transform

output

Of course, if no group keys, the result is only one row.

Best regards,

Simon