add jax.extend.random.wrap_key_data

jax/BUILD

@@ -153,6 +153,7 @@ py_library_providing_imports_info(
         [
             "*.py",
             "_src/debugger/**/*.py",
+            "_src/extend/**/*.py",
             "_src/image/**/*.py",
             "_src/lax/**/*.py",
             "_src/nn/**/*.py",

jax/_src/extend/__init__.py

@@ -0,0 +1,13 @@
+# Copyright 2023 The JAX Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.

jax/_src/extend/random.py

@@ -0,0 +1,23 @@
+# Copyright 2023 The JAX Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Optional
+
+from jax._src import prng
+from jax._src import random
+from jax._src.typing import Array
+
+def wrap_key_data(key_bits_array: Array, *, impl: Optional[str] = None):
+  impl_obj = random.resolve_prng_impl(impl)
+  return prng.random_wrap(key_bits_array, impl=impl_obj)

jax/extend/random.py

@@ -24,3 +24,7 @@ from jax._src.prng import (
   rbg_prng_impl as rbg_prng_impl,
   unsafe_rbg_prng_impl as unsafe_rbg_prng_impl,
 )
+
+from jax._src.extend.random import (
+  wrap_key_data as wrap_key_data,
+)

tests/extend_test.py

@@ -14,6 +14,7 @@
 
 from absl.testing import absltest
 
+import jax
 import jax.extend as jex
 
 from jax._src import prng
@@ -22,6 +23,7 @@ from jax._src import test_util as jtu
 from jax import config
 config.parse_flags_with_absl()
 
+
 class ExtendTest(jtu.JaxTestCase):
   def test_symbols(self):
     # Assume these are tested in random_test.py, only check equivalence
@@ -33,5 +35,33 @@ class ExtendTest(jtu.JaxTestCase):
     self.assertIs(jex.random.rbg_prng_impl, prng.rbg_prng_impl)
     self.assertIs(jex.random.unsafe_rbg_prng_impl, prng.unsafe_rbg_prng_impl)
 
+
+class RandomTest(jtu.JaxTestCase):
+  def test_wrap_key_default(self):
+    key1 = jax.random.key(17)
+    data = jax.random.key_data(key1)
+    key2 = jex.random.wrap_key_data(data)
+    self.assertEqual(key1.dtype, key2.dtype)
+    self.assertArraysEqual(jax.random.key_data(key1),
+                           jax.random.key_data(key2))
+
+    impl = config.jax_default_prng_impl
+    key3 = jex.random.wrap_key_data(data, impl=impl)
+    self.assertEqual(key1.dtype, key3.dtype)
+    self.assertArraysEqual(jax.random.key_data(key1),
+                           jax.random.key_data(key3))
+
+  def test_wrap_key_explicit(self):
+    key1 = jax.random.key(17, impl='rbg')
+    data = jax.random.key_data(key1)
+    key2 = jex.random.wrap_key_data(data, impl='rbg')
+    self.assertEqual(key1.dtype, key2.dtype)
+    self.assertArraysEqual(jax.random.key_data(key1),
+                           jax.random.key_data(key2))
+
+    key3 = jex.random.wrap_key_data(data, impl='unsafe_rbg')
+    self.assertNotEqual(key1.dtype, key3.dtype)
+
+
 if __name__ == "__main__":
   absltest.main(testLoader=jtu.JaxTestLoader())