BUG: Fix range dtype in constructor on windows

Author: jschendel

doc/source/whatsnew/v0.21.0.txt

@@ -918,6 +918,7 @@ Conversion
 - Bug in ``Timedelta`` construction and arithmetic that would not propagate the ``Overflow`` exception (:issue:`17367`)
 - Bug in :meth:`~DataFrame.astype` converting to object dtype when passed extension type classes (`DatetimeTZDtype``, ``CategoricalDtype``) rather than instances. Now a ``TypeError`` is raised when a class is passed (:issue:`17780`).
 - Bug in :meth:`to_numeric` in which elements were not always being coerced to numeric when ``errors='coerce'`` (:issue:`17007`, :issue:`17125`)
+- Bug in ``DataFrame`` and ``Series`` constructors where ``range`` objects are converted ``int32`` dtype on Windows instead of ``int64`` (:issue:`16804`)
 
 Indexing
 ^^^^^^^^

pandas/core/common.py

@@ -552,6 +552,30 @@ class Sentinel(object):
     return Sentinel()
 
 
+def _get_range_parameters(data):
+    """Gets the start, stop, and step parameters from a range object"""
+    if compat.PY3:
+        step = data.step
+        stop = data.stop
+        start = data.start
+    else:
+        # seems we only have indexing ops to infer
+        # rather than direct accessors
+        if len(data) > 1:
+            step = data[1] - data[0]
+            stop = data[-1] + step
+            start = data[0]
+        elif len(data):
+            start = data[0]
+            stop = data[0] + 1
+            step = 1
+        else:
+            start = stop = 0
+            step = 1
+
+    return start, stop, step
+
+
 # ----------------------------------------------------------------------
 # Detect our environment
 

pandas/core/indexes/range.py

@@ -12,7 +12,7 @@
 from pandas import compat
 from pandas.compat import lrange, range
 from pandas.compat.numpy import function as nv
-from pandas.core.common import _all_none
+from pandas.core.common import _all_none, _get_range_parameters
 from pandas.core.indexes.base import Index, _index_shared_docs
 from pandas.util._decorators import Appender, cache_readonly
 import pandas.core.dtypes.concat as _concat
@@ -113,24 +113,7 @@ def from_range(cls, data, name=None, dtype=None, **kwargs):
                 '{0}(...) must be called with object coercible to a '
                 'range, {1} was passed'.format(cls.__name__, repr(data)))
 
-        if compat.PY3:
-            step = data.step
-            stop = data.stop
-            start = data.start
-        else:
-            # seems we only have indexing ops to infer
-            # rather than direct accessors
-            if len(data) > 1:
-                step = data[1] - data[0]
-                stop = data[-1] + step
-                start = data[0]
-            elif len(data):
-                start = data[0]
-                stop = data[0] + 1
-                step = 1
-            else:
-                start = stop = 0
-                step = 1
+        start, stop, step = _get_range_parameters(data)
         return RangeIndex(start, stop, step, dtype=dtype, name=name, **kwargs)
 
     @classmethod

pandas/core/series.py

@@ -46,7 +46,8 @@
                                 _maybe_box_datetimelike,
                                 _dict_compat,
                                 standardize_mapping,
-                                _any_none)
+                                _any_none,
+                                _get_range_parameters)
 from pandas.core.index import (Index, MultiIndex, InvalidIndexError,
                                Float64Index, _ensure_index)
 from pandas.core.indexing import check_bool_indexer, maybe_convert_indices
@@ -3177,6 +3178,15 @@ def _try_cast(arr, take_fast_path):
 
         subarr = maybe_cast_to_datetime(subarr, dtype)
 
+    elif isinstance(data, range):
+        # GH 16804
+        start, stop, step = _get_range_parameters(data)
+        if is_extension_type(dtype):
+            arr = np.arange(start, stop, step, dtype='int64')
+            subarr = _try_cast(arr, False)
+        else:
+            subarr = np.arange(start, stop, step, dtype=dtype or 'int64')
+
     else:
         subarr = _try_cast(data, False)
 

pandas/tests/frame/test_constructors.py

@@ -829,7 +829,7 @@ def test_constructor_list_of_lists(self):
 
         # GH 4851
         # list of 0-dim ndarrays
-        expected = DataFrame({0: range(10)})
+        expected = DataFrame({0: np.arange(10)})
         data = [np.array(x) for x in range(10)]
         result = DataFrame(data)
         tm.assert_frame_equal(result, expected)
@@ -1927,6 +1927,17 @@ def test_to_frame_with_falsey_names(self):
         result = DataFrame(Series(name=0)).dtypes
         tm.assert_series_equal(result, expected)
 
+    def test_constructor_range_dtype(self):
+        # GH 16804
+        expected = DataFrame({'A': [0, 1, 2, 3, 4]}, dtype='int64')
+        result = DataFrame({'A': range(5)})
+        tm.assert_frame_equal(result, expected)
+
+        # override default dtype
+        expected = DataFrame({'A': [0, 1, 2, 3, 4]}, dtype='uint8')
+        result = DataFrame({'A': range(5)}, dtype='uint8')
+        tm.assert_frame_equal(result, expected)
+
 
 class TestDataFrameConstructorWithDatetimeTZ(TestData):
 

pandas/tests/indexing/test_partial.py

@@ -532,7 +532,7 @@ def f():
 
         def f():
             df = DataFrame()
-            df['foo'] = Series(range(len(df)))
+            df['foo'] = Series(np.arange(len(df)), dtype='float64')
             return df
 
         tm.assert_frame_equal(f(), expected)

pandas/tests/series/test_alter_axes.py

@@ -219,7 +219,7 @@ def test_reorder_levels(self):
                            labels=[[0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0],
                                    [0, 0, 0, 0, 0, 0]],
                            names=['L0', 'L0', 'L0'])
-        expected = Series(range(6), index=e_idx)
+        expected = Series(np.arange(6), index=e_idx)
         assert_series_equal(result, expected)
 
         result = s.reorder_levels(['L0', 'L0', 'L0'])

pandas/tests/series/test_constructors.py

@@ -846,3 +846,14 @@ def test_constructor_generic_timestamp_deprecated(self):
         msg = "cannot convert datetimelike"
         with tm.assert_raises_regex(TypeError, msg):
             Series([], dtype='M8[ps]')
+
+    def test_constructor_range_dtype(self):
+        # GH 16804
+        expected = Series([0, 1, 2, 3, 4], dtype='int64')
+        result = Series(range(5))
+        tm.assert_series_equal(result, expected)
+
+        # override default dtype
+        expected = Series([0, 1, 2, 3, 4], dtype='uint8')
+        result = Series(range(5), dtype='uint8')
+        tm.assert_series_equal(result, expected)

pandas/tests/test_common.py

@@ -7,7 +7,7 @@
 import numpy as np
 
 from pandas import Series, Timestamp
-from pandas.compat import range, lmap
+from pandas.compat import range, lmap, PY2
 import pandas.core.common as com
 import pandas.util.testing as tm
 
@@ -221,3 +221,20 @@ def test_standardize_mapping():
 
     dd = collections.defaultdict(list)
     assert isinstance(com.standardize_mapping(dd), partial)
+
+
+@pytest.mark.parametrize(
+    'start,stop,step', [(0, 10, 2), (11, -2, -1), (0, -5, 1), (2, 4, 8)])
+def test_get_range_parameters(start, stop, step):
+    rng = range(start, stop, step)
+    if PY2 and len(rng) == 0:
+        start_expected, stop_expected, step_expected = 0, 0, 1
+    elif PY2 and len(rng) == 1:
+        start_expected, stop_expected, step_expected = start, start + 1, 1
+    else:
+        start_expected, stop_expected, step_expected = start, stop, step
+
+    start_result, stop_result, step_result = com._get_range_parameters(rng)
+    assert start_result == start_expected
+    assert stop_result == stop_expected
+    assert step_result == step_expected

pandas/tests/test_resample.py

@@ -3030,7 +3030,7 @@ def test_nearest(self):
         # GH 17496
         # Resample nearest
         index = pd.date_range('1/1/2000', periods=3, freq='T')
-        result = pd.Series(range(3), index=index).resample('20s').nearest()
+        result = pd.Series(np.arange(3), index=index).resample('20s').nearest()
 
         expected = pd.Series(
             np.array([0, 0, 1, 1, 1, 2, 2]),

pandas/tests/test_window.py

@@ -698,8 +698,8 @@ def get_expects(self):
         return expects
 
     def _create_dtype_data(self, dtype):
-        sr1 = Series(range(5), dtype=dtype)
-        sr2 = Series(range(10, 0, -2), dtype=dtype)
+        sr1 = Series(np.arange(5), dtype=dtype)
+        sr2 = Series(np.arange(10, 0, -2), dtype=dtype)
         df = DataFrame(np.arange(10).reshape((5, 2)), dtype=dtype)
 
         data = {