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https://issues.apache.org/jira/browse/ARROW-2443?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16444138#comment-16444138
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ASF GitHub Bot commented on ARROW-2443:
---------------------------------------
pitrou closed pull request #1906: ARROW-2443: [Python] Allow creation of empty
Dictionary indices
URL: https://github.com/apache/arrow/pull/1906
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
below (as it won't show otherwise due to GitHub magic):
diff --git a/cpp/src/arrow/array.cc b/cpp/src/arrow/array.cc
index c3fb04bbc..710821e1d 100644
--- a/cpp/src/arrow/array.cc
+++ b/cpp/src/arrow/array.cc
@@ -581,10 +581,6 @@ DictionaryArray::DictionaryArray(const
std::shared_ptr<DataType>& type,
Status DictionaryArray::FromArrays(const std::shared_ptr<DataType>& type,
const std::shared_ptr<Array>& indices,
std::shared_ptr<Array>* out) {
- if (indices->length() == 0) {
- return Status::Invalid("Dictionary indices must have non-zero length");
- }
-
DCHECK_EQ(type->id(), Type::DICTIONARY);
const auto& dict = static_cast<const DictionaryType&>(*type);
DCHECK_EQ(indices->type_id(), dict.index_type()->id());
diff --git a/python/pyarrow/tests/test_convert_pandas.py
b/python/pyarrow/tests/test_convert_pandas.py
index 7f9ede969..6970975cc 100644
--- a/python/pyarrow/tests/test_convert_pandas.py
+++ b/python/pyarrow/tests/test_convert_pandas.py
@@ -1836,6 +1836,11 @@ def test_category(self):
for values in arrays:
_check_array_roundtrip(values)
+ def test_empty_category(self):
+ # ARROW-2443
+ df = pd.DataFrame({'cat': pd.Categorical([])})
+ _check_pandas_roundtrip(df)
+
def test_mixed_types_fails(self):
data = pd.DataFrame({'a': ['a', 1, 2.0]})
with pytest.raises(pa.ArrowException):
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> [Python] Conversion from pandas of empty categorical fails with ArrowInvalid
> ----------------------------------------------------------------------------
>
> Key: ARROW-2443
> URL: https://issues.apache.org/jira/browse/ARROW-2443
> Project: Apache Arrow
> Issue Type: Bug
> Affects Versions: 0.9.0
> Reporter: Florian Jetter
> Assignee: Uwe L. Korn
> Priority: Minor
> Labels: pull-request-available
> Fix For: 0.10.0
>
>
> The conversion of an empty pandas categorical raises an exception. Before
> version `0.9.0` this was possible
> {code:java}
> import pandas as pd
> import pyarrow as pa
> pa.Table.from_pandas(pd.DataFrame({'cat': pd.Categorical([])})){code}
> raises:
> {{ArrowInvalid: Dictionary indices must have non-zero length}}
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