breaking: Move _NPYSerializer to sagemaker.serializers and rename to NumpySerializer

src/sagemaker/chainer/model.py

@@ -25,7 +25,8 @@
 from sagemaker.model import FrameworkModel, MODEL_SERVER_WORKERS_PARAM_NAME
 from sagemaker.chainer import defaults
 from sagemaker.deserializers import NumpyDeserializer
-from sagemaker.predictor import Predictor, npy_serializer
+from sagemaker.predictor import Predictor
+from sagemaker.serializers import NumpySerializer
 
 logger = logging.getLogger("sagemaker")
 
@@ -49,7 +50,7 @@ def __init__(self, endpoint_name, sagemaker_session=None):
                 using the default AWS configuration chain.
         """
         super(ChainerPredictor, self).__init__(
-            endpoint_name, sagemaker_session, npy_serializer, NumpyDeserializer()
+            endpoint_name, sagemaker_session, NumpySerializer(), NumpyDeserializer()
         )
 
 

src/sagemaker/predictor.py

@@ -16,10 +16,10 @@
 import codecs
 import csv
 import json
-from six import StringIO, BytesIO
+from six import StringIO
 import numpy as np
 
-from sagemaker.content_types import CONTENT_TYPE_JSON, CONTENT_TYPE_CSV, CONTENT_TYPE_NPY
+from sagemaker.content_types import CONTENT_TYPE_JSON, CONTENT_TYPE_CSV
 from sagemaker.deserializers import BaseDeserializer
 from sagemaker.model_monitor import DataCaptureConfig
 from sagemaker.serializers import BaseSerializer
@@ -620,51 +620,3 @@ def __call__(self, stream, content_type):
 
 
 json_deserializer = _JsonDeserializer()
-
-
-class _NPYSerializer(object):
-    """Placeholder docstring"""
-
-    def __init__(self):
-        """Placeholder docstring"""
-        self.content_type = CONTENT_TYPE_NPY
-
-    def __call__(self, data, dtype=None):
-        """Serialize data into the request body in NPY format.
-
-        Args:
-            data (object): Data to be serialized. Can be a numpy array, list,
-                file, or buffer.
-            dtype:
-
-        Returns:
-            object: NPY serialized data used for the request.
-        """
-        if isinstance(data, np.ndarray):
-            if not data.size > 0:
-                raise ValueError("empty array can't be serialized")
-            return _npy_serialize(data)
-
-        if isinstance(data, list):
-            if not len(data) > 0:
-                raise ValueError("empty array can't be serialized")
-            return _npy_serialize(np.array(data, dtype))
-
-        # files and buffers. Assumed to hold npy-formatted data.
-        if hasattr(data, "read"):
-            return data.read()
-
-        return _npy_serialize(np.array(data))
-
-
-def _npy_serialize(data):
-    """
-    Args:
-        data:
-    """
-    buffer = BytesIO()
-    np.save(buffer, data)
-    return buffer.getvalue()
-
-
-npy_serializer = _NPYSerializer()

src/sagemaker/pytorch/model.py

@@ -26,7 +26,8 @@
 )
 from sagemaker.model import FrameworkModel, MODEL_SERVER_WORKERS_PARAM_NAME
 from sagemaker.pytorch import defaults
-from sagemaker.predictor import Predictor, npy_serializer
+from sagemaker.predictor import Predictor
+from sagemaker.serializers import NumpySerializer
 
 logger = logging.getLogger("sagemaker")
 
@@ -50,7 +51,7 @@ def __init__(self, endpoint_name, sagemaker_session=None):
                 using the default AWS configuration chain.
         """
         super(PyTorchPredictor, self).__init__(
-            endpoint_name, sagemaker_session, npy_serializer, NumpyDeserializer()
+            endpoint_name, sagemaker_session, NumpySerializer(), NumpyDeserializer()
         )
 
 

src/sagemaker/serializers.py

@@ -14,6 +14,7 @@
 from __future__ import absolute_import
 
 import abc
+import io
 import json
 
 import numpy as np
@@ -43,6 +44,59 @@ def CONTENT_TYPE(self):
         """The MIME type of the data sent to the inference endpoint."""
 
 
+class NumpySerializer(BaseSerializer):
+    """Serialize data to a buffer using the .npy format."""
+
+    CONTENT_TYPE = "application/x-npy"
+
+    def __init__(self, dtype=None):
+        """Initialize the dtype.
+
+        Args:
+            dtype (str): The dtype of the data.
+        """
+        self.dtype = dtype
+
+    def serialize(self, data):
+        """Serialize data to a buffer using the .npy format.
+
+        Args:
+            data (object): Data to be serialized. Can be a NumPy array, list,
+                file, or buffer.
+
+        Returns:
+            io.BytesIO: A buffer containing data serialzied in the .npy format.
+        """
+        if isinstance(data, np.ndarray):
+            if data.size == 0:
+                raise ValueError("Cannot serialize empty array.")
+            return self._serialize_array(data)
+
+        if isinstance(data, list):
+            if len(data) == 0:
+                raise ValueError("Cannot serialize empty array.")
+            return self._serialize_array(np.array(data, self.dtype))
+
+        # files and buffers. Assumed to hold npy-formatted data.
+        if hasattr(data, "read"):
+            return data.read()
+
+        return self._serialize_array(np.array(data))
+
+    def _serialize_array(self, array):
+        """Saves a NumPy array in a buffer.
+
+        Args:
+            array (numpy.ndarray): The array to serialize.
+
+        Returns:
+            io.BytesIO: A buffer containing the serialized array.
+        """
+        buffer = io.BytesIO()
+        np.save(buffer, array)
+        return buffer.getvalue()
+
+
 class JSONSerializer(BaseSerializer):
     """Serialize data to a JSON formatted string."""
 

src/sagemaker/sklearn/model.py

@@ -20,7 +20,8 @@
 from sagemaker.fw_registry import default_framework_uri
 from sagemaker.fw_utils import model_code_key_prefix, validate_version_or_image_args
 from sagemaker.model import FrameworkModel, MODEL_SERVER_WORKERS_PARAM_NAME
-from sagemaker.predictor import Predictor, npy_serializer
+from sagemaker.predictor import Predictor
+from sagemaker.serializers import NumpySerializer
 from sagemaker.sklearn import defaults
 
 logger = logging.getLogger("sagemaker")
@@ -45,7 +46,7 @@ def __init__(self, endpoint_name, sagemaker_session=None):
                 using the default AWS configuration chain.
         """
         super(SKLearnPredictor, self).__init__(
-            endpoint_name, sagemaker_session, npy_serializer, NumpyDeserializer()
+            endpoint_name, sagemaker_session, NumpySerializer(), NumpyDeserializer()
         )
 
 

src/sagemaker/xgboost/model.py

@@ -20,7 +20,8 @@
 from sagemaker.fw_utils import model_code_key_prefix
 from sagemaker.fw_registry import default_framework_uri
 from sagemaker.model import FrameworkModel, MODEL_SERVER_WORKERS_PARAM_NAME
-from sagemaker.predictor import Predictor, npy_serializer
+from sagemaker.predictor import Predictor
+from sagemaker.serializers import NumpySerializer
 from sagemaker.xgboost.defaults import XGBOOST_NAME
 
 logger = logging.getLogger("sagemaker")
@@ -43,7 +44,7 @@ def __init__(self, endpoint_name, sagemaker_session=None):
                 chain.
         """
         super(XGBoostPredictor, self).__init__(
-            endpoint_name, sagemaker_session, npy_serializer, CSVDeserializer()
+            endpoint_name, sagemaker_session, NumpySerializer(), CSVDeserializer()
         )
 
 

tests/integ/test_multidatamodel.py

@@ -27,7 +27,8 @@
 from sagemaker.deserializers import StringDeserializer
 from sagemaker.multidatamodel import MultiDataModel
 from sagemaker.mxnet import MXNet
-from sagemaker.predictor import Predictor, npy_serializer
+from sagemaker.predictor import Predictor
+from sagemaker.serializers import NumpySerializer
 from sagemaker.utils import sagemaker_timestamp, unique_name_from_base, get_ecr_image_uri_prefix
 from tests.integ import DATA_DIR, TRAINING_DEFAULT_TIMEOUT_MINUTES
 from tests.integ.retry import retries
@@ -158,7 +159,7 @@ def test_multi_data_model_deploy_pretrained_models(
         predictor = Predictor(
             endpoint_name=endpoint_name,
             sagemaker_session=sagemaker_session,
-            serializer=npy_serializer,
+            serializer=NumpySerializer(),
             deserializer=string_deserializer,
         )
 
@@ -216,7 +217,7 @@ def test_multi_data_model_deploy_pretrained_models_local_mode(container_image, s
         predictor = Predictor(
             endpoint_name=endpoint_name,
             sagemaker_session=multi_data_model.sagemaker_session,
-            serializer=npy_serializer,
+            serializer=NumpySerializer(),
             deserializer=string_deserializer,
         )
 
@@ -289,13 +290,13 @@ def test_multi_data_model_deploy_trained_model_from_framework_estimator(
         assert PRETRAINED_MODEL_PATH_1 in endpoint_models
         assert PRETRAINED_MODEL_PATH_2 in endpoint_models
 
-        # Define a predictor to set `serializer` parameter with npy_serializer
+        # Define a predictor to set `serializer` parameter with `NumpySerializer`
         # instead of `JSONSerializer` in the default predictor returned by `MXNetPredictor`
         # Since we are using a placeholder container image the prediction results are not accurate.
         predictor = Predictor(
             endpoint_name=endpoint_name,
             sagemaker_session=sagemaker_session,
-            serializer=npy_serializer,
+            serializer=NumpySerializer(),
             deserializer=string_deserializer,
         )
 
@@ -390,13 +391,13 @@ def test_multi_data_model_deploy_train_model_from_amazon_first_party_estimator(
         assert PRETRAINED_MODEL_PATH_1 in endpoint_models
         assert PRETRAINED_MODEL_PATH_2 in endpoint_models
 
-        # Define a predictor to set `serializer` parameter with npy_serializer
+        # Define a predictor to set `serializer` parameter with `NumpySerializer`
         # instead of `JSONSerializer` in the default predictor returned by `MXNetPredictor`
         # Since we are using a placeholder container image the prediction results are not accurate.
         predictor = Predictor(
             endpoint_name=endpoint_name,
             sagemaker_session=sagemaker_session,
-            serializer=npy_serializer,
+            serializer=NumpySerializer(),
             deserializer=string_deserializer,
         )
 
@@ -486,7 +487,7 @@ def test_multi_data_model_deploy_pretrained_models_update_endpoint(
         predictor = Predictor(
             endpoint_name=endpoint_name,
             sagemaker_session=sagemaker_session,
-            serializer=npy_serializer,
+            serializer=NumpySerializer(),
             deserializer=string_deserializer,
         )
 

tests/unit/sagemaker/test_serializers.py

@@ -12,16 +12,100 @@
 # language governing permissions and limitations under the License.
 from __future__ import absolute_import
 
+import io
 import json
 import os
 
 import numpy as np
 import pytest
 
-from sagemaker.serializers import JSONSerializer
+from sagemaker.serializers import NumpySerializer, JSONSerializer
 from tests.unit import DATA_DIR
 
 
+@pytest.fixture
+def numpy_serializer():
+    return NumpySerializer()
+
+
+def test_numpy_serializer_python_array(numpy_serializer):
+    array = [1, 2, 3]
+    result = numpy_serializer.serialize(array)
+
+    assert np.array_equal(array, np.load(io.BytesIO(result)))
+
+
+def test_numpy_serializer_python_array_with_dtype():
+    numpy_serializer = NumpySerializer(dtype="float16")
+    array = [1, 2, 3]
+
+    result = numpy_serializer.serialize(array)
+
+    deserialized = np.load(io.BytesIO(result))
+    assert np.array_equal(array, deserialized)
+    assert deserialized.dtype == "float16"
+
+
+def test_numpy_serializer_numpy_valid_2_dimensional(numpy_serializer):
+    array = np.array([[1, 2, 3], [3, 4, 5]])
+    result = numpy_serializer.serialize(array)
+
+    assert np.array_equal(array, np.load(io.BytesIO(result)))
+
+
+def test_numpy_serializer_numpy_valid_multidimensional(numpy_serializer):
+    array = np.ones((10, 10, 10, 10))
+    result = numpy_serializer.serialize(array)
+
+    assert np.array_equal(array, np.load(io.BytesIO(result)))
+
+
+def test_numpy_serializer_numpy_valid_list_of_strings(numpy_serializer):
+    array = np.array(["one", "two", "three"])
+    result = numpy_serializer.serialize(array)
+
+    assert np.array_equal(array, np.load(io.BytesIO(result)))
+
+
+def test_numpy_serializer_from_buffer_or_file(numpy_serializer):
+    array = np.ones((2, 3))
+    stream = io.BytesIO()
+    np.save(stream, array)
+    stream.seek(0)
+
+    result = numpy_serializer.serialize(stream)
+
+    assert np.array_equal(array, np.load(io.BytesIO(result)))
+
+
+def test_numpy_serializer_object(numpy_serializer):
+    object = {1, 2, 3}
+
+    result = numpy_serializer.serialize(object)
+
+    assert np.array_equal(np.array(object), np.load(io.BytesIO(result), allow_pickle=True))
+
+
+def test_numpy_serializer_list_of_empty(numpy_serializer):
+    with pytest.raises(ValueError) as invalid_input:
+        numpy_serializer.serialize(np.array([[], []]))
+
+    assert "empty array" in str(invalid_input)
+
+
+def test_numpy_serializer_numpy_invalid_empty(numpy_serializer):
+    with pytest.raises(ValueError) as invalid_input:
+        numpy_serializer.serialize(np.array([]))
+
+    assert "empty array" in str(invalid_input)
+
+
+def test_numpy_serializer_python_invalid_empty(numpy_serializer):
+    with pytest.raises(ValueError) as error:
+        numpy_serializer.serialize([])
+    assert "empty array" in str(error)
+
+
 @pytest.fixture
 def json_serializer():
     return JSONSerializer()