jorisvandenbossche commented on a change in pull request #11624:
URL: https://github.com/apache/arrow/pull/11624#discussion_r753103114



##########
File path: python/pyarrow/table.pxi
##########
@@ -2387,3 +2429,60 @@ def _from_pydict(cls, mapping, schema, metadata):
         return cls.from_arrays(arrays, schema=schema, metadata=metadata)
     else:
         raise TypeError('Schema must be an instance of pyarrow.Schema')
+
+
+class TableGroupBy:
+    """
+    A grouping of columns in a table on which to perform aggregations.
+    """
+
+    def __init__(self, table, keys):
+        if isinstance(keys, str):
+            keys = [keys]
+
+        self._table = table
+        self.keys = keys
+
+    def aggregate(self, aggregations):
+        """
+        Perform an aggregation over the grouped columns of the table.
+
+        Parameters
+        ----------
+        aggregations : list[tuple(str, str)] or\
+                       list[tuple(str, str, FunctionOptions)]
+            List of tuples made of aggregation functions names followed
+            by column names and optionally aggregation function options.

Review comment:
       > Well, in pandas it's reversed because the aggregations are keyed by 
the column
   
   That's for the interface when specifying a dictionary. But in pandas you can 
also do something like `.agg(b_sum=('b', 'sum'))`, in which case it is a bit 
more similar as here. 




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