[GitHub] [arrow] pitrou commented on a diff in pull request #13327: ARROW-16706: [Python] Expose RankOptions

[GitBox <gi...@apache.org>]

pitrou commented on code in PR #13327:
URL: https://github.com/apache/arrow/pull/13327#discussion_r891392053


##########
python/pyarrow/_compute.pyx:
##########
@@ -2047,6 +2047,60 @@ class RandomOptions(_RandomOptions):
         self._set_options(length, initializer)
 
 
+cdef class _RankOptions(FunctionOptions):
+
+    _tiebreaker_map = {
+        "Min": CRankOptionsTiebreaker_MIN,
+        "Max": CRankOptionsTiebreaker_MAX,
+        "First": CRankOptionsTiebreaker_FIRST,
+        "Dense": CRankOptionsTiebreaker_DENSE,
+    }
+
+    def _set_options(self, sort_keys, null_placement, tiebreaker):
+        cdef vector[CSortKey] c_sort_keys
+        for name, order in sort_keys:
+            c_sort_keys.push_back(
+                CSortKey(tobytes(name), unwrap_sort_order(order))
+            )
+        try:
+            self.wrapped.reset(
+                new CRankOptions(c_sort_keys, unwrap_null_placement(null_placement), self._tiebreaker_map[tiebreaker])
+            )
+        except KeyError:
+            _raise_invalid_function_option(tiebreaker, "tiebreaker")
+
+
+class RankOptions(_RankOptions):
+    """
+    Options for the `rank` function.
+
+    Parameters
+    ----------
+    sort_keys : sequence of (name, order) tuples

Review Comment:
   It would be nice to be able to pass a simpler signature for the simple case of computing ranks on an array (which is the only thing supported currently, anyway). For example, the `sort_keys` default could be to do an ascending rank on an unnamed column.
   
   cc @jorisvandenbossche for suggestions and opinions



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