BUG: melt method doesn't seem to preserve timezone settings. · Issue #55254 · pandas-dev/pandas (original) (raw)

Pandas version checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pandas.
• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd

df = pd.DataFrame(data=[ {'type': 'A0', 'start_date': pd.Timestamp('2023/03/01', tz='Asia/Tokyo'), 'end_date': pd.Timestamp('2023/03/10', tz='Asia/Tokyo')}, {'type': 'A1', 'start_date': pd.Timestamp('2023/03/01', tz='Asia/Tokyo'), 'end_date': pd.Timestamp('2023/03/11', tz='Asia/Tokyo')}, ], index=['aaaa', 'bbbb']) display(df)

df = df.melt(id_vars=['type'], value_vars=['start_date', 'end_date'], var_name='start/end', value_name='date') display(df)

Issue Description

The melt method doesn't seem to preserve timezone settings.

Expected Behavior

Even after executing the melt method, it is desirable that the time zone settings remain the same as before executing the melt method.

Installed Versions

Name: pandas
Version: 2.1.1
Summary: Powerful data structures for data analysis, time series, and statistics
Home-page: https://pandas.pydata.org/
Author:
Author-email: The Pandas Development Team pandas-dev@python.org
License: BSD 3-Clause License

    Copyright (c) 2008-2011, AQR Capital Management, LLC, Lambda Foundry, Inc. and PyData Development Team
    All rights reserved.
    
    Copyright (c) 2011-2023, Open source contributors.
    
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:
    
    * Redistributions of source code must retain the above copyright notice, this
      list of conditions and the following disclaimer.
    
    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
    
    * Neither the name of the copyright holder nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.
    
    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
    OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Location: /home/sasaki/workspace/orcas_proj/venv/lib/python3.10/site-packages
Requires: numpy, python-dateutil, pytz, tzdata
Required-by: bokeh, mplfinance, seaborn