[jira] [Commented] (ARROW-2265) [Python] Serializing subclasses of np.ndarray returns a np.ndarray.

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-2265?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16387154#comment-16387154 ] 

ASF GitHub Bot commented on ARROW-2265:
---------------------------------------

wesm closed pull request #1704: ARROW-2265: [Python] Use CheckExact when serializing lists and numpy arrays.
URL: https://github.com/apache/arrow/pull/1704
 
 
   

This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:

As this is a foreign pull request (from a fork), the diff is supplied
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diff --git a/cpp/src/arrow/python/python_to_arrow.cc b/cpp/src/arrow/python/python_to_arrow.cc
index 6d4f64675..d781d9f0f 100644
--- a/cpp/src/arrow/python/python_to_arrow.cc
+++ b/cpp/src/arrow/python/python_to_arrow.cc
@@ -501,7 +501,7 @@ Status Append(PyObject* context, PyObject* elem, SequenceBuilder* builder,
       return Status::Invalid("Cannot writes bytes over 2GB");
     }
     RETURN_NOT_OK(builder->AppendString(data, static_cast<int32_t>(size)));
-  } else if (PyList_Check(elem)) {
+  } else if (PyList_CheckExact(elem)) {
     RETURN_NOT_OK(builder->AppendList(PyList_Size(elem)));
     sublists->push_back(elem);
   } else if (PyDict_CheckExact(elem)) {
@@ -515,7 +515,7 @@ Status Append(PyObject* context, PyObject* elem, SequenceBuilder* builder,
     subsets->push_back(elem);
   } else if (PyArray_IsScalar(elem, Generic)) {
     RETURN_NOT_OK(AppendScalar(elem, builder));
-  } else if (PyArray_Check(elem)) {
+  } else if (PyArray_CheckExact(elem)) {
     RETURN_NOT_OK(SerializeArray(context, reinterpret_cast<PyArrayObject*>(elem), builder,
                                  subdicts, blobs_out));
   } else if (elem == Py_None) {
diff --git a/python/pyarrow/tests/test_serialization.py b/python/pyarrow/tests/test_serialization.py
index 72315d2dc..c17408457 100644
--- a/python/pyarrow/tests/test_serialization.py
+++ b/python/pyarrow/tests/test_serialization.py
@@ -410,6 +410,33 @@ def deserialize_dummy_class(serialized_obj):
     pa.serialize(DummyClass(), context=context)
 
 
+def test_numpy_subclass_serialization():
+    # Check that we can properly serialize subclasses of np.ndarray.
+    class CustomNDArray(np.ndarray):
+        def __new__(cls, input_array):
+            array = np.asarray(input_array).view(cls)
+            return array
+
+    def serializer(obj):
+        return {'numpy': obj.view(np.ndarray)}
+
+    def deserializer(data):
+        array = data['numpy'].view(CustomNDArray)
+        return array
+
+    context = pa.default_serialization_context()
+
+    context.register_type(CustomNDArray, 'CustomNDArray',
+                          custom_serializer=serializer,
+                          custom_deserializer=deserializer)
+
+    x = CustomNDArray(np.zeros(3))
+    serialized = pa.serialize(x, context=context).to_buffer()
+    new_x = pa.deserialize(serialized, context=context)
+    assert type(new_x) == CustomNDArray
+    assert np.alltrue(new_x.view(np.ndarray) == np.zeros(3))
+
+
 def test_buffer_serialization():
 
     class BufferClass(object):


 

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> [Python] Serializing subclasses of np.ndarray returns a np.ndarray.
> -------------------------------------------------------------------
>
>                 Key: ARROW-2265
>                 URL: https://issues.apache.org/jira/browse/ARROW-2265
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>            Reporter: Robert Nishihara
>            Assignee: Robert Nishihara
>            Priority: Minor
>              Labels: pull-request-available
>             Fix For: 0.9.0
>
>




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