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https://issues.apache.org/jira/browse/ARROW-1763?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16248868#comment-16248868
]
ASF GitHub Bot commented on ARROW-1763:
---------------------------------------
xhochy closed pull request #1308: ARROW-1763: [Python] Implement __hash__ for
DataType
URL: https://github.com/apache/arrow/pull/1308
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/python/pyarrow/tests/test_types.py
b/python/pyarrow/tests/test_types.py
index 0e3ea1fd4..9eefa33b6 100644
--- a/python/pyarrow/tests/test_types.py
+++ b/python/pyarrow/tests/test_types.py
@@ -137,3 +137,27 @@ def test_is_temporal_date_time_timestamp():
def test_timestamp_type():
# See ARROW-1683
assert isinstance(pa.timestamp('ns'), pa.TimestampType)
+
+
+def test_types_hashable():
+ types = [
+ pa.null(),
+ pa.int32(),
+ pa.time32('s'),
+ pa.time64('us'),
+ pa.date32(),
+ pa.timestamp('us'),
+ pa.string(),
+ pa.binary(),
+ pa.binary(10),
+ pa.list_(pa.int32()),
+ pa.struct([pa.field('a', pa.int32()),
+ pa.field('b', pa.int8()),
+ pa.field('c', pa.string())])
+ ]
+
+ in_dict = {}
+ for i, type_ in enumerate(types):
+ assert hash(type_) == hash(type_)
+ in_dict[type_] = i
+ assert in_dict[type_] == i
diff --git a/python/pyarrow/types.pxi b/python/pyarrow/types.pxi
index d2e68ff79..edf0d8a30 100644
--- a/python/pyarrow/types.pxi
+++ b/python/pyarrow/types.pxi
@@ -69,6 +69,9 @@ cdef class DataType:
)
return frombytes(self.type.ToString())
+ def __hash__(self):
+ return hash(str(self))
+
def __reduce__(self):
return self.__class__, (), self.__getstate__()
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> [Python] DataType should be hashable
> ------------------------------------
>
> Key: ARROW-1763
> URL: https://issues.apache.org/jira/browse/ARROW-1763
> Project: Apache Arrow
> Issue Type: Improvement
> Reporter: Jeff Reback
> Assignee: Wes McKinney
> Labels: pull-request-available
> Fix For: 0.8.0
>
>
> We can then use the DataType objects as keys in dictionary for example. xref
> https://github.com/ibis-project/ibis/pull/1194#discussion_r148493472
> {code}
> In [1]: import pyarrow as pa
> In [2]: pa.__version__
> Out[2]: '0.7.1'
> In [3]: pa.int8()
> Out[3]: DataType(int8)
> In [4]: hash(pa.int8())
> ---------------------------------------------------------------------------
> TypeError Traceback (most recent call last)
> <ipython-input-4-bca0e6e2f6af> in <module>()
> ----> 1 hash(pa.int8())
> TypeError: unhashable type: 'pyarrow.lib.DataType'
> {code}
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