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PERF: don't call RangeIndex._data unnecessarily #26565

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Merged
merged 4 commits into from
Jun 1, 2019
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PERF: don't call RangeIndex._data unnecessarily #26565

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eadbdf3
PERF: don't call RangeIndex._data unneccesary
topper-123 May 29, 2019
803a97d
guard against invalid key
topper-123 May 29, 2019
a74db3f
changes
topper-123 May 31, 2019
c72758b
Doc string changes
topper-123 Jun 1, 2019
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@topper-123
topper-123 committed Jun 1, 2019
commit c72758b8e2d24a33ba95abb8d9d032d98268cff4
7 changes: 7 additions & 0 deletions pandas/core/indexes/range.py
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Expand Up @@ -188,6 +188,13 @@ def _constructor(self):

@property
def _data(self):
"""
An int array that for performance reasons is created only when needed.

The constructed array is saved in ``_cached_data``. This allows us to
check if the array has been created without accessing ``_data`` and
triggering the construction.
"""
if self._cached_data is None:
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can you give this a doc-string (e.g. that cached_data is actually an int array and be constructed only if necessary for performance reasons

self._cached_data = np.arange(self._start, self._stop, self._step,
dtype=np.int64)
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1 change: 1 addition & 0 deletions pandas/tests/indexes/test_range.py
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Expand Up @@ -242,6 +242,7 @@ def test_dtype(self):
assert self.index.dtype == np.int64

def test_cached_data(self):
# GH 26565
# Calling RangeIndex._data caches an int64 array of the same length at
# self._cached_data. This tests whether _cached_data has been set.
idx = RangeIndex(0, 100, 10)
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