DataFrame groupby partially drops timezone info (to_csv, in notebook)

[Poquaruse]

Hi all,

I've encountered a problem with DataFrames, groupby and timezones.

import pandas as pd import numpy as np

dt_rng = pd.date_range(start='2014-01-01 00:00', periods = 1000, freq='1s', tz='Europe/Berlin') df = pd.DataFrame({'a':np.random.randn(1000), 'b': np.random.randn(1000)},index = dt_rng) df['b'] = df['b'].round() df.to_csv()

--> Timezones are shown in the csv output, for example 2014-01-01 00:00:00+01:00

Now with resampling:

dt_rng = pd.date_range(start='2014-01-01 00:00', periods = 1000, freq='1s', tz='Europe/Berlin') df = pd.DataFrame({'a':np.random.randn(1000), 'b': np.random.randn(1000)},index = dt_rng) df['b'] = df['b'].round() df.groupby(df['b']).resample('1min').to_csv()

--> 2013-12-31 23:01:00 no timezone info, not even UTC.

However:

dt_rng = pd.date_range(start='2014-01-01 00:00', periods = 1000, freq='1s', tz='Europe/Berlin') df = pd.DataFrame({'a':np.random.randn(1000), 'b': np.random.randn(1000)},index = dt_rng) df['b'] = df['b'].round() df.groupby(df['b']).resample('1min').index.levels[1]

shows: Timezone: Europe/Berlin

So the info seems to be there, but is not exported - even if it was exported before without resampling...

Any ideas?

Thanks and best regards

[jreback]

pls post pd.show_versions()

[Poquaruse]

Sorry, I forgot. Here it is:

INSTALLED VERSIONS

commit: None python: 3.4.1.final.0 python-bits: 64 OS: Windows OS-release: 8 machine: AMD64 processor: Intel64 Family 6 Model 58 Stepping 9, GenuineIntel byteorder: little LC_ALL: None LANG: None

pandas: 0.14.0 nose: 1.3.3 Cython: 0.20.1 numpy: 1.8.1 scipy: 0.14.0 statsmodels: None IPython: 2.1.0 sphinx: 1.2.2 patsy: 0.2.1 scikits.timeseries: None dateutil: 2.1 pytz: 2014.3 bottleneck: None tables: 3.1.1 numexpr: 2.3.1 matplotlib: 1.3.1 openpyxl: 1.8.5 xlrd: 0.9.3 xlwt: None xlsxwriter: 0.5.5 lxml: 3.3.5 bs4: 4.3.1 html5lib: None bq: None apiclient: None rpy2: None sqlalchemy: 0.9.4 pymysql: None psycopg2: None

[jreback]

this works in master, lots of bugs related to tz preservation are fixed for 0.14.1 (releasing soon)

[Poquaruse]

Thanks for the heads up! :-)