DataFrame.resample week with DST

[maartenhollenga]

Code Sample

import pandas
import pytz

dataframe_1 = pandas.DataFrame(index=pandas.DatetimeIndex(
    ['2017-03-04 00:00', '2017-03-05 00:00', '2017-03-06 00:00', '2017-03-07 00:00', '2017-03-08 00:00'],
    tz=pytz.timezone('Europe/Amsterdam')),
    data=[11, 12, 13, 14, 15])
resampled_1 = dataframe_1.resample('1W').sum()
print(resampled_1)

dataframe_2 = pandas.DataFrame(index=pandas.DatetimeIndex(
    ['2017-03-25 00:00', '2017-03-26 00:00', '2017-03-27 00:00', '2017-03-28 00:00', '2017-03-29 00:00'],
    tz=pytz.timezone('Europe/Amsterdam')),
    data=[11, 12, 13, 14, 15])
resampled_2 = dataframe_2.resample('1W').sum()
print(resampled_2)

dataframe_3 = pandas.DataFrame(index=pandas.DatetimeIndex(
    ['2017-04-15 00:00', '2017-04-16 00:00', '2017-04-17 00:00', '2017-04-18 00:00', '2017-04-19 00:00'],
    tz=pytz.timezone('Europe/Amsterdam')),
    data=[11, 12, 13, 14, 15])
resampled_3 = dataframe_3.resample('1W').sum()
print(resampled_3)

Problem description

It looks like there is something wrong with pandas.DataFrame.resample (by week) in relation to DST.
When I run the above code sample I expect three times the same output, but the DST starting week
(dataframe_2 ) differ from the regular weeks.

Actual Output

                            0
2017-03-05 00:00:00+01:00  23
2017-03-12 00:00:00+01:00  42
                            0
2017-03-26 00:00:00+01:00  36
2017-04-02 00:00:00+02:00  29
                            0
2017-04-16 00:00:00+02:00  23
2017-04-23 00:00:00+02:00  42

Expected Output

                            0
2017-03-05 00:00:00+01:00  23
2017-03-12 00:00:00+01:00  42
                            0
2017-03-26 00:00:00+01:00  23
2017-04-02 00:00:00+02:00  42
                            0
2017-04-16 00:00:00+02:00  23
2017-04-23 00:00:00+02:00  42

Output of pd.show_versions()

commit: None python: 3.6.4.final.0 python-bits: 64 OS: Darwin OS-release: 16.7.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: None LOCALE: en_US.UTF-8

pandas: 0.23.1
pytest: None
pip: 10.0.0
setuptools: 28.8.0
Cython: None
numpy: 1.14.1
scipy: None
pyarrow: None
xarray: None
IPython: None
sphinx: None
patsy: None
dateutil: 2.6.1
pytz: 2018.3
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: 1.0.2
lxml: None
bs4: None
html5lib: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: None
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

[gfyoung]

cc @jreback

[mroeschke]

Just posting for posterity; this issue and similarly #9119 can be solved if this branch is skipped:

pandas/pandas/core/resample.py

Line 1400 in a936399

if self.freq != 'D' and is_superperiod(self.freq, 'D'):

But I am still unsure of the logic behind why this branch exists.