From 5aabc85e76f3f95291a7d975b0bd26a401986776 Mon Sep 17 00:00:00 2001 From: Matt Roeschke Date: Mon, 19 Feb 2018 09:50:06 -0800 Subject: [PATCH] BUG: DataFrame.diff(axis=0) with DatetimeTZ data add whatsnew clarify comment Add addtional tests move diff into its own function in DatetimeTZBlock Use correct placement fix failing test formatting --- doc/source/whatsnew/v0.23.0.txt | 1 + pandas/core/internals.py | 12 ++++++++++++ pandas/tests/frame/test_timeseries.py | 23 +++++++++++++++++++++++ 3 files changed, 36 insertions(+) diff --git a/doc/source/whatsnew/v0.23.0.txt b/doc/source/whatsnew/v0.23.0.txt index 7f33372f765fb3..e88ae82ca30142 100644 --- a/doc/source/whatsnew/v0.23.0.txt +++ b/doc/source/whatsnew/v0.23.0.txt @@ -798,6 +798,7 @@ Timezones - Bug in the :class:`DataFrame` constructor, where tz-aware Datetimeindex and a given column name will result in an empty ``DataFrame`` (:issue:`19157`) - Bug in :func:`Timestamp.tz_localize` where localizing a timestamp near the minimum or maximum valid values could overflow and return a timestamp with an incorrect nanosecond value (:issue:`12677`) - Bug when iterating over :class:`DatetimeIndex` that was localized with fixed timezone offset that rounded nanosecond precision to microseconds (:issue:`19603`) +- Bug in :func:`DataFrame.diff` that raised an ``IndexError`` with tz-aware values (:issue:`18578`) Offsets ^^^^^^^ diff --git a/pandas/core/internals.py b/pandas/core/internals.py index 00ef8f9cef5985..9ba60f540cf0b7 100644 --- a/pandas/core/internals.py +++ b/pandas/core/internals.py @@ -2905,6 +2905,18 @@ def shift(self, periods, axis=0, mgr=None): return [self.make_block_same_class(new_values, placement=self.mgr_locs)] + def diff(self, n, axis=0, mgr=None): + """1st discrete difference""" + if axis == 0: + # Cannot currently calculate diff across multiple blocks since this + # function is invoked via apply + raise NotImplementedError + new_values = (self.values - self.shift(n, axis=axis)[0].values).asi8 + # Reshape the new_values like how algos.diff does for timedelta data + new_values = new_values.reshape(1, len(new_values)) + new_values = new_values.astype('timedelta64[ns]') + return [TimeDeltaBlock(new_values, placement=self.mgr_locs.indexer)] + def concat_same_type(self, to_concat, placement=None): """ Concatenate list of single blocks of the same type. diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py index e1bc310e1e9347..5114815ddf178d 100644 --- a/pandas/tests/frame/test_timeseries.py +++ b/pandas/tests/frame/test_timeseries.py @@ -57,6 +57,29 @@ def test_diff(self): 1), 'z': pd.Series(1)}).astype('float64') assert_frame_equal(result, expected) + @pytest.mark.parametrize('axis', [0, 1]) + @pytest.mark.parametrize('tz', [None, 'UTC']) + def test_diff_datetime(self, axis, tz): + # GH 18578 + df = DataFrame({0: date_range('2010', freq='D', periods=2, tz=tz), + 1: date_range('2010', freq='D', periods=2, tz=tz)}) + if axis == 1: + if tz is None: + result = df.diff(axis=axis) + expected = DataFrame({0: pd.TimedeltaIndex(['NaT', 'NaT']), + 1: pd.TimedeltaIndex(['0 days', + '0 days'])}) + assert_frame_equal(result, expected) + else: + with pytest.raises(NotImplementedError): + result = df.diff(axis=axis) + + else: + result = df.diff(axis=axis) + expected = DataFrame({0: pd.TimedeltaIndex(['NaT', '1 days']), + 1: pd.TimedeltaIndex(['NaT', '1 days'])}) + assert_frame_equal(result, expected) + def test_diff_timedelta(self): # GH 4533 df = DataFrame(dict(time=[Timestamp('20130101 9:01'),