describe() does not report first and last on tz-aware datetime Series

[louispotok]

Code Sample, a copy-pastable example if possible

s = pd.Series(pd.date_range("2018-01-01","2018-01-05"))
s.describe() # includes first and last
s.dt.tz_localize('US/Eastern').describe() # does not include first and last

Problem description

The describe method on a timezone-naive datetime Series reports the "first" (min) and "last" (max) values. I would expect the same to be true for a timezone-aware datetime Series, since min and max are defined there as well.

Output of pd.show_versions()

INSTALLED VERSIONS

commit: None
python: 3.6.4.final.0
python-bits: 64
OS: Linux
OS-release: 4.13.0-43-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.23.0
pytest: 3.4.2
pip: 9.0.1
setuptools: 38.4.0
Cython: None
numpy: 1.14.3
scipy: 1.1.0
pyarrow: 0.9.0
xarray: None
IPython: 6.2.1
sphinx: 1.7.3
patsy: 0.5.0
dateutil: 2.7.3
pytz: 2018.4
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: 0.4.0
matplotlib: 2.1.2
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: 1.0.1
sqlalchemy: 1.2.7
pymysql: None
psycopg2: 2.7.4 (dt dec pq3 ext lo64)
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

[mroeschke]

Thanks for the report; that definitely sounds reasonable. This block below needs some additional logic to handle timezone aware datetimes:

pandas/pandas/core/generic.py

Lines 8533 to 8538 in 7dc6f70

	if is_datetime64_dtype(data):
	asint = data.dropna().values.view('i8')
	names += ['top', 'freq', 'first', 'last']
	result += [tslib.Timestamp(top), freq,
	tslib.Timestamp(asint.min()),
	tslib.Timestamp(asint.max())]

Pull requests are welcome!

[louispotok]

Right, looks like replacing that check with is_datetime64_any_dtype would catch the tz-aware ones.

Thanks, I'll try to get a PR in soon.