ASF GitHub Bot commented on ARROW-2101:

joshuastorck commented on issue #1886: ARROW-2101: [Python/C++] Correctly 
convert numpy arrays of bytes to arrow arrays of strings when user specifies 
arrow type of string
URL: https://github.com/apache/arrow/pull/1886#issuecomment-381263228
   I built for Python 2 and confirmed the behavior is the same. 
   @pitrou, in regards to the inefficiency of utf-8 encoding, it could be moved 
below to the check of global_have_bytes. Would you prefer this?
     if (global_have_bytes) {
       if (force_string)
           PyObject* obj;
        Ndarray1DIndexer<PyObject*> objects(arr_);
        Ndarray1DIndexer<uint8_t> mask_values;
        bool have_mask = false;
        if (mask_ != nullptr) {
          have_mask = true;
        PyBytesView view;
        for (int64_t offset = 0; offset < objects.size(); ++offset) {
          OwnedRef tmp_obj;
          obj = objects[offset];
          if ((have_mask && mask_values[offset]) || 
internal::PandasObjectIsNull(obj)) {
             RETURN_NOT_OK(view.FromString(obj, true);
         for (size_t i = 0; i < out_arrays_.size(); ++i) {
        auto binary_data = out_arrays_[i]->data()->Copy();c
        binary_data->type = ::arrow::binary();
        out_arrays_[i] = std::make_shared<BinaryArray>(binary_data);
   I'm not fond of how much code I had to copy from AppendObjectStrings to 
write that loop. I think it would be helpful to have iterators that look like 
   NdArray1DIndexer<PyObject*> array(array_);
   auto mask = NdArray1DIndexer<uint64_t>::from_mask(mask_);
   NdArray1DMaskedIterator iterator(array.begin() + offset, array.end(), mask, 
true /* include masked value */);
   for (OwnedRef& obj: iterator)
      // Maybe we use None to indicate masked values?
   Or even better, we use pybind11 and these are light wrappers over them?

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> [Python] from_pandas reads 'str' type as binary Arrow data with Python 2
> ------------------------------------------------------------------------
>                 Key: ARROW-2101
>                 URL: https://issues.apache.org/jira/browse/ARROW-2101
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>    Affects Versions: 0.8.0
>            Reporter: Bryan Cutler
>            Assignee: Bryan Cutler
>            Priority: Major
>              Labels: pull-request-available
> Using Python 2, converting Pandas with 'str' data to Arrow results in Arrow 
> data of binary type, even if the user supplies type information.  conversion 
> of 'unicode' type works to create Arrow data of string types.  For example
> {code}
> In [25]: pa.Array.from_pandas(pd.Series(['a'])).type
> Out[25]: DataType(binary)
> In [26]: pa.Array.from_pandas(pd.Series(['a']), type=pa.string()).type
> Out[26]: DataType(binary)
> In [27]: pa.Array.from_pandas(pd.Series([u'a'])).type
> Out[27]: DataType(string)
> {code}

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