Improved error message for zero k

Author: ankane

ext/faiss/index_binary.cpp

@@ -65,8 +65,8 @@ void init_index_binary(Rice::Module& m) {
       [](Rice::Object rb_self, numo::UInt8 objects, int64_t k) {
         auto& self = *Rice::Data_Object<faiss::IndexBinary>{rb_self};
         size_t n = check_shape(objects, self.d / 8);
-        if (k < 0) {
-          throw Rice::Exception(rb_eArgError, "expected k to be non-negative");
+        if (k <= 0) {
+          throw Rice::Exception(rb_eArgError, "expected k to be positive");
         }
 
         numo::Int32 distances{{n, static_cast<size_t>(k)}};

ext/faiss/index_rb.cpp

@@ -156,8 +156,8 @@ void init_index(Rice::Module& m) {
       [](Rice::Object rb_self, numo::SFloat objects, int64_t k) {
         auto& self = *Rice::Data_Object<faiss::Index>{rb_self};
         size_t n = check_shape(objects, self.d);
-        if (k < 0) {
-          throw Rice::Exception(rb_eArgError, "expected k to be non-negative");
+        if (k <= 0) {
+          throw Rice::Exception(rb_eArgError, "expected k to be positive");
         }
 
         numo::SFloat distances{{n, static_cast<size_t>(k)}};

test/index_binary_test.rb

@@ -56,6 +56,21 @@ def test_remove_ids
     assert_equal [1, 0, -1], ids[0, true].to_a
   end
 
+  def test_search_zero_k
+    objects = [
+      [1, 1, 2, 1],
+      [5, 4, 6, 5],
+      [1, 2, 1, 2]
+    ]
+    index = Faiss::IndexBinaryFlat.new(32)
+    index.add(objects)
+
+    error = assert_raises(ArgumentError) do
+      index.search(objects, 0)
+    end
+    assert_equal "expected k to be positive", error.message
+  end
+
   def test_search_negative_k
     objects = [
       [1, 1, 2, 1],
@@ -68,7 +83,7 @@ def test_search_negative_k
     error = assert_raises(ArgumentError) do
       index.search(objects, -1)
     end
-    assert_equal "expected k to be non-negative", error.message
+    assert_equal "expected k to be positive", error.message
   end
 
   def test_add_frozen

test/index_test.rb

@@ -336,6 +336,21 @@ def test_remove_ids_empty
     assert_equal 0, index.remove_ids([])
   end
 
+  def test_search_zero_k
+    objects = [
+      [1, 1, 2, 1],
+      [5, 4, 6, 5],
+      [1, 2, 1, 2]
+    ]
+    index = Faiss::IndexFlatL2.new(4)
+    index.add(objects)
+
+    error = assert_raises(ArgumentError) do
+      index.search(objects, 0)
+    end
+    assert_equal "expected k to be positive", error.message
+  end
+
   def test_search_negative_k
     objects = [
       [1, 1, 2, 1],
@@ -348,7 +363,7 @@ def test_search_negative_k
     error = assert_raises(ArgumentError) do
       index.search(objects, -1)
     end
-    assert_equal "expected k to be non-negative", error.message
+    assert_equal "expected k to be positive", error.message
   end
 
   def test_add_frozen