From 7cb402a3b468dfddd13abddaf4d7e2dbdc294917 Mon Sep 17 00:00:00 2001
From: Anton Volkov <antonwolfy@gmail.com>
Date: Mon, 21 Jul 2025 15:42:15 +0200
Subject: [PATCH 1/4] Add __contains__() method

---
 dpnp/dpnp_array.py         |  4 +++-
 dpnp/tests/test_ndarray.py | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/dpnp/dpnp_array.py b/dpnp/dpnp_array.py
index 791b2a8178c4..3e100952785e 100644
--- a/dpnp/dpnp_array.py
+++ b/dpnp/dpnp_array.py
@@ -242,7 +242,9 @@ def __bool__(self):
     def __complex__(self):
         return self._array_obj.__complex__()
 
-    # '__contains__',
+    def __contains__(self, key, /):
+        """Return :math:`key in self`."""
+        return (self == key).any()
 
     def __copy__(self):
         """
diff --git a/dpnp/tests/test_ndarray.py b/dpnp/tests/test_ndarray.py
index eaccf689a795..90b4045f62f9 100644
--- a/dpnp/tests/test_ndarray.py
+++ b/dpnp/tests/test_ndarray.py
@@ -74,6 +74,39 @@ def test_attributes(self):
         assert_equal(self.two.itemsize, self.two.dtype.itemsize)
 
 
+@testing.parameterize(*testing.product({"xp": [dpnp, numpy]}))
+class TestContains:
+    def test_basic(self):
+        a = self.xp.arange(10).reshape((2, 5))
+        assert 4 in a
+        assert 20 not in a
+
+    def test_broadcast(self):
+        xp = self.xp
+        a = xp.arange(6).reshape((2, 3))
+        assert 4 in a
+        assert xp.array([0, 1, 2]) in a
+        assert xp.array([5, 3, 4]) not in a
+
+    def test_broadcast_error(self):
+        a = self.xp.arange(10).reshape((2, 5))
+        with pytest.raises(
+            ValueError,
+            match="operands could not be broadcast together with shapes",
+        ):
+            self.xp.array([1, 2]) in a
+
+    def test_strides(self):
+        xp = self.xp
+        a = xp.arange(10).reshape((2, 5))
+        a = a[:, ::2]
+        assert 4 in a
+        assert 8 not in a
+        assert xp.full(a.shape[-1], fill_value=2) in a
+        assert xp.full_like(a, fill_value=7) in a
+        assert xp.full_like(a, fill_value=6) not in a
+
+
 class TestView:
     def test_none_dtype(self):
         a = numpy.ones((1, 2, 4), dtype=numpy.int32)

From 3ab8fdea32fae38054a093dc4388b55944cd3140 Mon Sep 17 00:00:00 2001
From: Anton Volkov <antonwolfy@gmail.com>
Date: Mon, 21 Jul 2025 15:44:06 +0200
Subject: [PATCH 2/4] Add PR to the changelog

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 97c45c670ba8..38b2c20b7647 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added a new backend routine `syrk` from oneMKL to perform symmetric rank-k update which is used for a specialized matrix multiplication where the result is a symmetric matrix [2509](https://github.com/IntelPython/dpnp/pull/2509)
 * Added `timeout-minutes` property to GitHub jobs [#2526](https://github.com/IntelPython/dpnp/pull/2526)
 * Added implementation of `dpnp.ndarray.data` and `dpnp.ndarray.data.ptr` attributes [#2521](https://github.com/IntelPython/dpnp/pull/2521)
+* Added `dpnp.ndarray.__contains__` method [#2534](https://github.com/IntelPython/dpnp/pull/2534)
 
 ### Changed
 

From c103a0face6d8f55d1a20520c003b70e0f059dfe Mon Sep 17 00:00:00 2001
From: Anton Volkov <antonwolfy@gmail.com>
Date: Mon, 21 Jul 2025 15:47:43 +0200
Subject: [PATCH 3/4] Rename argument to `value` aligning with the latest NumPy
 changes

---
 dpnp/dpnp_array.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/dpnp/dpnp_array.py b/dpnp/dpnp_array.py
index 3e100952785e..ec536713eb76 100644
--- a/dpnp/dpnp_array.py
+++ b/dpnp/dpnp_array.py
@@ -242,9 +242,9 @@ def __bool__(self):
     def __complex__(self):
         return self._array_obj.__complex__()
 
-    def __contains__(self, key, /):
-        """Return :math:`key in self`."""
-        return (self == key).any()
+    def __contains__(self, value, /):
+        """Return :math:`value in self`."""
+        return (self == value).any()
 
     def __copy__(self):
         """

From 5c683f3e43ca18942583ae9d2d3e31b4c6ea39a4 Mon Sep 17 00:00:00 2001
From: Anton Volkov <antonwolfy@gmail.com>
Date: Mon, 21 Jul 2025 16:36:39 +0200
Subject: [PATCH 4/4] Use plain text inside a math expression

---
 dpnp/dpnp_array.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dpnp/dpnp_array.py b/dpnp/dpnp_array.py
index ec536713eb76..a70a4e99e668 100644
--- a/dpnp/dpnp_array.py
+++ b/dpnp/dpnp_array.py
@@ -243,7 +243,7 @@ def __complex__(self):
         return self._array_obj.__complex__()
 
     def __contains__(self, value, /):
-        """Return :math:`value in self`."""
+        r"""Return :math:`\text{value in self}`."""
         return (self == value).any()
 
     def __copy__(self):