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new 90d9daf ARROW-2129: [Python] Handle conversion of empty tables to
Pandas
90d9daf is described below
commit 90d9daf1419fdff5fd295053dcad756d1cdb3931
Author: Uwe L. Korn <uw...@xhochy.com>
AuthorDate: Mon Feb 12 09:55:09 2018 -0500
ARROW-2129: [Python] Handle conversion of empty tables to Pandas
Opened https://issues.apache.org/jira/browse/ARROW-2133 to handle the
nested case.
Author: Uwe L. Korn <uw...@xhochy.com>
Closes #1588 from xhochy/ARROW-2129 and squashes the following commits:
78b62d3f [Uwe L. Korn] Use Pandas' testing facilities
8287d034 [Uwe L. Korn] ARROW-2129: [Python] Handle conversion of empty
tables to Pandas
---
cpp/src/arrow/python/arrow_to_pandas.cc | 11 ++++++++---
python/pyarrow/tests/test_convert_pandas.py | 6 ++++++
2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/cpp/src/arrow/python/arrow_to_pandas.cc
b/cpp/src/arrow/python/arrow_to_pandas.cc
index 60a2eae..0488989 100644
--- a/cpp/src/arrow/python/arrow_to_pandas.cc
+++ b/cpp/src/arrow/python/arrow_to_pandas.cc
@@ -280,6 +280,9 @@ class PandasBlock {
template <typename T>
inline const T* GetPrimitiveValues(const Array& arr) {
+ if (arr.length() == 0) {
+ return nullptr;
+ }
const auto& prim_arr = static_cast<const PrimitiveArray&>(arr);
const T* raw_values = reinterpret_cast<const T*>(prim_arr.values()->data());
return raw_values + arr.offset();
@@ -304,9 +307,11 @@ inline void ConvertIntegerNoNullsSameType(PandasOptions
options, const ChunkedAr
T* out_values) {
for (int c = 0; c < data.num_chunks(); c++) {
const auto& arr = *data.chunk(c);
- const T* in_values = GetPrimitiveValues<T>(arr);
- memcpy(out_values, in_values, sizeof(T) * arr.length());
- out_values += arr.length();
+ if (arr.length() > 0) {
+ const T* in_values = GetPrimitiveValues<T>(arr);
+ memcpy(out_values, in_values, sizeof(T) * arr.length());
+ out_values += arr.length();
+ }
}
}
diff --git a/python/pyarrow/tests/test_convert_pandas.py
b/python/pyarrow/tests/test_convert_pandas.py
index edb6051..b825dfc 100644
--- a/python/pyarrow/tests/test_convert_pandas.py
+++ b/python/pyarrow/tests/test_convert_pandas.py
@@ -1346,6 +1346,12 @@ class TestPandasConversion(object):
_check_pandas_roundtrip(df2, preserve_index=True)
_check_pandas_roundtrip(df2, as_batch=True, preserve_index=True)
+ def test_convert_empty_table(self):
+ arr = pa.array([], type=pa.int64())
+ tm.assert_almost_equal(arr.to_pandas(), np.array([], dtype=np.int64))
+ arr = pa.array([], type=pa.string())
+ tm.assert_almost_equal(arr.to_pandas(), np.array([], dtype=object))
+
def test_array_from_pandas_date_with_mask(self):
m = np.array([True, False, True])
data = pd.Series([
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