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https://issues.apache.org/jira/browse/ARROW-2142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16389414#comment-16389414
 ] 

ASF GitHub Bot commented on ARROW-2142:
---------------------------------------

pitrou commented on a change in pull request #1635: ARROW-2142: [Python] Allow 
conversion from Numpy struct array
URL: https://github.com/apache/arrow/pull/1635#discussion_r172811688
 
 

 ##########
 File path: cpp/src/arrow/python/numpy_to_arrow.cc
 ##########
 @@ -1590,6 +1592,85 @@ Status NumPyConverter::Visit(const StringType& type) {
   return PushArray(result->data());
 }
 
+Status NumPyConverter::Visit(const StructType& type) {
+  std::vector<NumPyConverter> sub_converters;
+  std::vector<OwnedRefNoGIL> sub_arrays;
+
+  {
+    PyAcquireGIL gil_lock;
+
+    // Create converters for each struct type field
+    if (dtype_->fields == NULL || !PyDict_Check(dtype_->fields)) {
+      return Status::TypeError("Expected struct array");
+    }
+
+    for (auto field : type.children()) {
+      PyObject* tup = PyDict_GetItemString(dtype_->fields, 
field->name().c_str());
 
 Review comment:
   On Python 3, yes, a unicode object is constructed assuming a UTF-8 input 
(using `PyUnicode_FromString`). On Python 2, a bytes object is constructed for 
lookup, and any non-ASCII bytes-unicode comparison would fail.

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> [Python] Conversion from Numpy struct array unimplemented
> ---------------------------------------------------------
>
>                 Key: ARROW-2142
>                 URL: https://issues.apache.org/jira/browse/ARROW-2142
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Python
>    Affects Versions: 0.8.0
>            Reporter: Antoine Pitrou
>            Assignee: Antoine Pitrou
>            Priority: Major
>              Labels: pull-request-available
>
> {code:python}
> >>> arr = np.array([(1.5,)], dtype=np.dtype([('x', np.float32)]))
> >>> arr
> array([(1.5,)], dtype=[('x', '<f4')])
> >>> arr[0]
> (1.5,)
> >>> arr['x']
> array([1.5], dtype=float32)
> >>> arr['x'][0]
> 1.5
> >>> pa.array(arr, type=pa.struct([pa.field('x', pa.float32())]))
> Traceback (most recent call last):
>   File "<ipython-input-18-27a52820b7d8>", line 1, in <module>
>     pa.array(arr, type=pa.struct([pa.field('x', pa.float32())]))
>   File "array.pxi", line 177, in pyarrow.lib.array
>   File "error.pxi", line 77, in pyarrow.lib.check_status
>   File "error.pxi", line 85, in pyarrow.lib.check_status
> ArrowNotImplementedError: 
> /home/antoine/arrow/cpp/src/arrow/python/numpy_to_arrow.cc:1585 code: 
> converter.Convert()
> NumPyConverter doesn't implement <struct<x: float>> conversion.
> {code}



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