Add client support for SeriesGroupby unique, nsmallest, nlargest (mod…

…in-project#63) [core]

* Add client support for SeriesGroupby unique, nsmallest, nlargest

Signed-off-by: Naren Krishna <naren@ponder.io>

---------

Signed-off-by: Naren Krishna <naren@ponder.io>

modin/pandas/groupby.py

@@ -1434,6 +1434,32 @@ def _iter(self):
                 for k in (sorted(group_ids) if self._sort else group_ids)
             )
 
+    def unique(self):
+        return self._check_index(
+            self._wrap_aggregation(
+                type(self._query_compiler).groupby_unique,
+                numeric_only=False,
+            )
+        )
+
+    def nlargest(self, n=5, keep="first"):
+        return self._check_index(
+            self._wrap_aggregation(
+                type(self._query_compiler).groupby_nlargest,
+                agg_kwargs=dict(n=n, keep=keep),
+                numeric_only=True,
+            )
+        )
+
+    def nsmallest(self, n=5, keep="first"):
+        return self._check_index(
+            self._wrap_aggregation(
+                type(self._query_compiler).groupby_nsmallest,
+                agg_kwargs=dict(n=n, keep=keep),
+                numeric_only=True,
+            )
+        )
+
     def value_counts(
         self,
         normalize: bool = False,