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Merged
merged 7 commits into from
May 12, 2018
Merged

ENH: Raise useful error when iterating a Window #20996

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ENH: Raise useful error when iterating a Window
selik May 9, 2018
9fd89dc
Test that iteration raises NotImplemented
selik May 10, 2018
4ac67f0
Note window iteration raises NotImplemented
selik May 10, 2018
15224fe
switch % to .format
selik May 10, 2018
4b44b05
style change as per suggestion
selik May 12, 2018
1bcaa7f
fix testfunc parameters
selik May 12, 2018
6bd748d
s/cls/klass/g
selik May 12, 2018
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2 changes: 1 addition & 1 deletion doc/source/whatsnew/v0.23.0.txt
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Expand Up @@ -966,7 +966,7 @@ Other API Changes
- Constructing a Series from a list of length 1 no longer broadcasts this list when a longer index is specified (:issue:`19714`, :issue:`20391`).
- :func:`DataFrame.to_dict` with ``orient='index'`` no longer casts int columns to float for a DataFrame with only int and float columns (:issue:`18580`)
- A user-defined-function that is passed to :func:`Series.rolling().aggregate() <pandas.core.window.Rolling.aggregate>`, :func:`DataFrame.rolling().aggregate() <pandas.core.window.Rolling.aggregate>`, or its expanding cousins, will now *always* be passed a ``Series``, rather than a ``np.array``; ``.apply()`` only has the ``raw`` keyword, see :ref:`here <whatsnew_0230.enhancements.window_raw>`. This is consistent with the signatures of ``.aggregate()`` across pandas (:issue:`20584`)
- Window types, such as Rolling and Expanding, raise `NotImplementedError` upon iteration. This will ideally be replaced by mimicking the (key, group) iteration of GroupBy (:issue:`11704`).
- Rolling and Expanding types raise ``NotImplementedError`` upon iteration (:issue:`11704`).

.. _whatsnew_0230.deprecations:

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37 changes: 16 additions & 21 deletions pandas/tests/test_window.py
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Expand Up @@ -46,27 +46,6 @@ def win_types_special(request):
return request.param


# Issue 11704: Iteration over a Window

@pytest.fixture
def series():
return pd.Series([1, 2, 3, 4])

@pytest.fixture
def frame():
return pd.DataFrame({'a': [1, 2, 3, 4], 'b': [10, 20, 30, 40]})

@pytest.mark.parametrize('which', [series(), frame()])
def test_rolling_iterator(which):
with pytest.raises(NotImplementedError):
iter(which.rolling(2))

@pytest.mark.parametrize('which', [series(), frame()])
def test_expanding_iterator(which):
with pytest.raises(NotImplementedError):
iter(which.expanding())


class Base(object):

_nan_locs = np.arange(20, 40)
Expand Down Expand Up @@ -533,6 +512,14 @@ def test_multi_index_names(self):
tm.assert_index_equal(result.columns, df.columns)
assert result.index.names == [None, '1', '2']

@pytest.mark.parametrize('cls', [pd.Series, pd.DataFrame])
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Can you use "klass" instead of "cls"

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@selik selik May 12, 2018 •
edited
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I strongly prefer cls in this case. Certain misspellings have a distasteful cultural undertone for me. Also, cls is an equally popular standard in other Python projects, if not more popular.

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"klass" is most used in pandas so we should stick with that as the standard for now (thought admittedly not 100%). If you feel so inclined you can definitely bring up the conversation to standard as an issue or on the mailing list and get feedback.

Would be easier to change in one sweep that having each contributor implement their own standard

grep "parametrize.*klass" -r pandas/tests/ | wc -l
      38
grep "parametrize.*box" -r pandas/tests/ | wc -l
      12
grep "parametrize.*cls" -r pandas/tests/ | wc -l
      10

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Ok, I'll make that change separately.

def test_iter_raises(cls):
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Missing "self" as first argument

# https://github.com/pandas-dev/pandas/issues/11704
# Iteration over a Window
obj = cls([1, 2, 3, 4])
with pytest.raises(NotImplementedError):
iter(obj.rolling(2))


class TestExpanding(Base):

Expand Down Expand Up @@ -611,6 +598,14 @@ def test_missing_minp_zero(self):
expected = pd.Series([np.nan])
tm.assert_series_equal(result, expected)

@pytest.mark.parametrize('cls', [pd.Series, pd.DataFrame])
def test_iter_raises(cls):
# https://github.com/pandas-dev/pandas/issues/11704
# Iteration over a Window
obj = cls([1, 2, 3, 4])
with pytest.raises(NotImplementedError):
iter(obj.expanding(2))


class TestEWM(Base):

Expand Down