pyodc

A Python interface to odc for encoding/decoding ODB-2 files.

The package contains two different implementations of the same library:

• pyodc is a pure-python encoder and decoder for ODB-2 data, which encodes data from, and decodes it into pandas data frames
• codc is an implementation of the same API as pyodc that depends on the ECMWF odc library, and comes with much better performance

Documentation Changelog

Dependencies

Required

• Python 3.x

Optional

• odc
• pytest
• pandoc
• Jupyter Notebook

For codc to work, odc library must be compiled and installed on the system and made available to Python (through the CFFI mechanism) as a shared library. There are multiple ways to make the library visible to CFFI: it can be installed as a system library, the installation prefix can be passed in the odc_DIR or ODC_DIR environment variables, or the library directory can be included in LD_LIBRARY_PATH.

Installation

pip install --user pyodc

Check if the module was installed correctly:

python
>>> import pyodc
>>> import codc # optional

Usage

An introductory Jupyter Notebook with helpful usage examples is provided in the root of this repository:

git clone git@github.com:ecmwf/pyodc.git
cd pyodc
jupyter notebook Introduction.ipynb

Development

Run Unit Tests

To run the unit tests, make sure that the pytest module is installed first:

python -m pytest

Build Documentation

To build the documentation locally, please install the Python dependencies first:

cd docs
pip install -r requirements.txt
make html

The built HTML documentation will be available under the docs/_build/html/index.html path.

License

This software is licensed under the terms of the Apache Licence Version 2.0 which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.

In applying this licence, ECMWF does not waive the privileges and immunities granted to it by virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.

Changelog for pyodc

1.1.3

• Improved github/ci integration

1.1.2

• Fixed #6: pip install breaks codc

1.1.1

• Fixed ODB-534: PyPI package is missing CHANGELOG

1.1.0

• Fixed ODB-533: Decode data starting with missing values correctly
• Fixed ODB-530: Bitfield column inspection returns incomplete data in pure-Python implementation
• Bumped up required odc version number to 1.4.0
• Added missing frame properties accessor to codc interface
• Fixed ODB-525: Setting odc prefix variable (odc_DIR) does not work as expected on macOS
• Fixed ODB-524: Keys and values in decoded frame properties are switched on older Python version
• Added test flag to skip codc tests on demand (PYODC_SKIP_CODC)
• Fixed ODB-523: Additional properties parameter is omitted in encode_odb() when string is passed as file
• Fixed package setup metadata
• Added documentation

1.0.4

• Correct support for constant codecs
• Decoding by column short name

1.0.3

• Specify odc library location with odc/ODC_DIR
• Correct setup.py dependencies to include pandas
• Support missing ConstantString values encoded from ODB1 using the odb_migrator

1.0.2

• String missing values should be None not NaN
• Refactor oneshot behaviour (read_odb_oneshot --> read_odb(..., single=True))
• Raise correct error on odc not found
• Split codb.py into a full codc module
• Fix miscellaneous bugs

1.0.1

• Fixed automatic selection of integral codecs

1.0.0

• Initial version