From eeac48961b901ec28adc9a78a3fc63d0e4f5d92e Mon Sep 17 00:00:00 2001
From: Wenlei Xie <wxie@fb.com>
Date: Wed, 22 Jun 2022 23:17:40 -0700
Subject: [PATCH] Add clamp_list UDF (#397)

Summary:
Pull Request resolved: https://github.com/pytorch/torcharrow/pull/397

Basically apply clamp to each element in the list.  Used for sparse feature preproc in recommendation domain.

This UDF will be deprecated once TorchArrow supports lambda function.

Reviewed By: bearzx

Differential Revision: D37370459

fbshipit-source-id: f64d59129dd980f886241ce1ac8cfaee251c0a01
---
 csrc/velox/functions/CMakeLists.txt          |  5 +-
 csrc/velox/functions/functions.h             | 29 +++++++++++
 csrc/velox/functions/rec/clamp_list.h        | 37 ++++++++++++++
 torcharrow/test/transformation/test_clamp.py | 53 ++++++++++++++++++++
 4 files changed, 122 insertions(+), 2 deletions(-)
 create mode 100644 csrc/velox/functions/rec/clamp_list.h
 create mode 100644 torcharrow/test/transformation/test_clamp.py

diff --git a/csrc/velox/functions/CMakeLists.txt b/csrc/velox/functions/CMakeLists.txt
index 0c4012456..c1931a13f 100644
--- a/csrc/velox/functions/CMakeLists.txt
+++ b/csrc/velox/functions/CMakeLists.txt
@@ -13,14 +13,15 @@ set(
   rec/sigrid_hash.h
   rec/firstX.h
   rec/compute_score.h
+  rec/clamp_list.h
   register_udf.cpp
-  )
+)
 
 set(
   TORCHARROW_UDF_LINK_LIBRARIES
   velox_functions_string
   velox_functions_prestosql
-  )
+)
 set(TORCHARROW_UDF_COMPILE_DEFINITIONS)
 
 if (USE_TORCH)
diff --git a/csrc/velox/functions/functions.h b/csrc/velox/functions/functions.h
index ba7b99627..f0ecddecb 100644
--- a/csrc/velox/functions/functions.h
+++ b/csrc/velox/functions/functions.h
@@ -11,6 +11,7 @@
 #include <velox/functions/Registerer.h>
 #include "numeric_functions.h"
 #include "rec/bucketize.h" // @manual
+#include "rec/clamp_list.h" // @manual
 #include "rec/compute_score.h" // @manual
 #include "rec/firstX.h" // @manual
 #include "rec/sigrid_hash.h" // @manual
@@ -368,6 +369,34 @@ inline void registerTorchArrowFunctions() {
       velox::Array<int64_t>,
       velox::Array<float>>({"get_score_max"});
 
+  velox::registerFunction<
+      ClampListFunction,
+      velox::Array<int32_t>,
+      velox::Array<int32_t>,
+      int32_t,
+      int32_t>({"clamp_list"});
+
+  velox::registerFunction<
+      ClampListFunction,
+      velox::Array<int64_t>,
+      velox::Array<int64_t>,
+      int64_t,
+      int64_t>({"clamp_list"});
+
+  velox::registerFunction<
+      ClampListFunction,
+      velox::Array<float>,
+      velox::Array<float>,
+      float,
+      float>({"clamp_list"});
+
+  velox::registerFunction<
+      ClampListFunction,
+      velox::Array<double>,
+      velox::Array<double>,
+      double,
+      double>({"clamp_list"});
+
   // TODO: consider to refactor registration code with helper functions
   // to save some lines, like https://fburl.com/code/dk6zi7t3
 
diff --git a/csrc/velox/functions/rec/clamp_list.h b/csrc/velox/functions/rec/clamp_list.h
new file mode 100644
index 000000000..56b41bc79
--- /dev/null
+++ b/csrc/velox/functions/rec/clamp_list.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <cmath>
+#include "velox/functions/Udf.h"
+#include "velox/type/Type.h"
+
+namespace facebook::torcharrow::functions {
+
+// TODO: remove this function once lambda expression is supported in
+// TorchArrow
+template <typename T>
+struct ClampListFunction {
+  VELOX_DEFINE_FUNCTION_TYPES(T);
+
+  template <typename TOutput, typename TInput, typename TElement>
+  FOLLY_ALWAYS_INLINE void callNullFree(
+      TOutput& result,
+      const TInput& values,
+      const TElement& lo,
+      const TElement& hi) {
+    VELOX_USER_CHECK_LE(lo, hi, "Lo > hi in clamp.");
+    result.reserve(values.size());
+    for (const auto& val : values) {
+      result.push_back(std::clamp(val, lo, hi));
+    }
+  }
+};
+
+} // namespace facebook::torcharrow::functions
diff --git a/torcharrow/test/transformation/test_clamp.py b/torcharrow/test/transformation/test_clamp.py
new file mode 100644
index 000000000..2a534b9be
--- /dev/null
+++ b/torcharrow/test/transformation/test_clamp.py
@@ -0,0 +1,53 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+import unittest
+
+import torcharrow as ta
+import torcharrow.dtypes as dt
+from torcharrow import functional
+
+
+class _TestClampBase(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.base_df_list = ta.dataframe(
+            {
+                "int64": [[0, 1, 2, 3], [-100, 100, 10], [0, -1, -2, -3]],
+            },
+            dtype=dt.Struct(
+                fields=[
+                    dt.Field("int64", dt.List(dt.int64)),
+                ]
+            ),
+        )
+
+        cls.setUpTestCaseData()
+
+    @classmethod
+    def setUpTestCaseData(cls):
+        # Override in subclass
+        # Python doesn't have native "abstract base test" support.
+        # So use unittest.SkipTest to skip in base class: https://stackoverflow.com/a/59561905.
+        raise unittest.SkipTest("abstract base test")
+
+    def test_clamp_list(self):
+        df = type(self).df_list
+
+        self.assertEqual(
+            list(functional.clamp_list(df["int64"], 0, 20)),
+            [[0, 1, 2, 3], [0, 20, 10], [0, 0, 0, 0]],
+        )
+
+
+class TestClampCpu(_TestClampBase):
+    @classmethod
+    def setUpTestCaseData(cls):
+        cls.df_list = cls.base_df_list.copy()
+
+
+if __name__ == "__main__":
+    unittest.main()