jorisvandenbossche commented on code in PR #34759:
URL: https://github.com/apache/arrow/pull/34759#discussion_r1150583383
##########
python/pyarrow/table.pxi:
##########
@@ -5515,6 +5515,9 @@ list[tuple(str, str, FunctionOptions)]
column names, for unary, nullary and n-ary aggregation functions
respectively.
+ For the list of function names and respective aggregation
+ function options see: :ref:`py-grouped-aggrs`.
Review Comment:
```suggestion
function options see :ref:`py-grouped-aggrs`.
```
##########
python/pyarrow/table.pxi:
##########
@@ -5527,20 +5530,58 @@ list[tuple(str, str, FunctionOptions)]
... pa.array(["a", "a", "b", "b", "c"]),
... pa.array([1, 2, 3, 4, 5]),
... ], names=["keys", "values"])
+
+ Sum the column "values" over the grouped column "keys":
+
>>> t.group_by("keys").aggregate([("values", "sum")])
pyarrow.Table
values_sum: int64
keys: string
----
values_sum: [[3,7,5]]
keys: [["a","b","c"]]
+
+ Count the rows over the grouped column "keys":
+
>>> t.group_by("keys").aggregate([([], "count_all")])
pyarrow.Table
count_all: int64
keys: string
----
count_all: [[2,2,1]]
keys: [["a","b","c"]]
+
+ Do multiple aggregations:
+
+ >>> t.group_by("keys").aggregate([
+ ... ("values", "sum"),
+ ... ("keys", "count")
+ ... ])
+ pyarrow.Table
+ values_sum: int64
+ keys_count: int64
+ keys: string
+ ----
+ values_sum: [[3,7,5]]
+ keys_count: [[2,2,1]]
+ keys: [["a","b","c"]]
+
+ Count the number of non-null values for column "values"
+ over the grouped column "keys":
+
+ >>> import pyarrow.compute as pc
+ >>> t.group_by(["keys"]).aggregate([
+ ... ("values", "count", pc.CountOptions(mode="all"))
Review Comment:
```suggestion
... ("values", "count", pc.CountOptions(mode="only_valid"))
```
If you want the "number of non-null values" as mentioned above, you need
this option (which is actually the default, but OK to show it explicitly I
think)
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