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Python interface to the ecCodes GRIB and BUFR decoder/encoder

Project description

Python 3 interface to decode and encode GRIB and BUFR files via the ECMWF ecCodes library.


  • reads and writes GRIB 1 and 2 files,

  • reads and writes BUFR 3 and 4 files,

  • supports all modern versions of Python 3.7, 3.6, 3.5 and PyPy3,

  • works on most Linux distributions and MacOS, the ecCodes C-library is the only system dependency,

  • PyPI package can be installed without compiling, at the cost of being twice as slow as the original ecCodes module,

  • an optional compile step makes the code as fast as the original module but it needs the recommended (the most up-to-date) version of ecCodes.


  • Microsoft Windows support is untested.


The package is installed from PyPI with:

$ pip install eccodes

System dependencies

The Python module depends on the ECMWF ecCodes library that must be installed on the system and accessible as a shared library.

On a MacOS with HomeBrew use:

$ brew install eccodes

Or if you manage binary packages with Conda use:

$ conda install -c conda-forge eccodes

As an alternative you may install the official source distribution by following the instructions at

You may run a simple selfcheck command to ensure that your system is set up correctly:

$ python -m eccodes selfcheck
Found: ecCodes v2.18.0.
Your system is ready.


Refer to the ecCodes documentation pages for usage.

Experimental features

Fast bindings

To test the much faster CFFI API level, out-of-line mode you need the ecCodes header files. Then you need to clone the repo in the same folder as your ecCodes source tree, make a pip development install and custom compile the binary bindings:

$ git clone
$ cd eccodes-python
$ pip install -e .
$ python

To revert back to ABI level, in-line more just remove the compiled bindings:

$ rm gribapi/_bindings.*

Project resources



Code quality

Build Status on Travis CI Coverage Status on Coveralls


The main repository is hosted on GitHub, testing, bug reports and contributions are highly welcomed and appreciated:

Please see the CONTRIBUTING.rst document for the best way to help.



See also the list of contributors who participated in this project.


  1. Copyright 2017- ECMWF.

This software is licensed under the terms of the Apache Licence Version 2.0 which can be obtained at

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 eccodes-python

0.9.8 (2020-MM-DD)

  • ECC-1110: Removed obsolete function codes_close_file()

  • Provide missing argument to exceptions

  • Fix codes_set_definitions_path() typo

  • Fix grib_get_double_element(). Missing last argument

  • Add more tests to increase coverage

  • Add .__next__() method to eccodes.CodesFile class (pull request #15)

  • ECC-1113: Python3 bindings under Windows: codes_get_long_array returns incorrect values

  • ECC-1108: Python3 bindings under Windows: use of handle causes crash

  • ECC-1121: Segfault when closing GribFile if messages are closed manually

0.9.6 (2020-03-10)

  • Update Copyright notices

  • Function-argument type checks: Improve error message

  • Fix C function calls for codes_gribex_mode_on/codes_gribex_mode_off

0.9.5 (2020-01-15)

  • ECC-1029: Function-argument type-checking should be disabled by default.

    To enable these checks, export ECCODES_PYTHON_ENABLE_TYPE_CHECKS=1

  • ECC-1032: Added codes_samples_path() and codes_definition_path()

  • ECC-1042: Python3 interface writes integer arrays incorrectly

  • ECC-794: Python3 interface: Expose the grib_get_data function

0.9.4 (2019-11-27)

  • Added new function: codes_get_version_info

  • ECC-753: Expose the codes_grib_nearest_find_multiple function in Python

  • ECC-1007: Python3 interface for eccodes cannot write large arrays

0.9.3 (2019-10-04)

  • New exception added: FunctionalityNotEnabledError

  • BUFR decoding: support for multi-element constant arrays (ECC-428)

0.9.2 (2019-07-09)

  • All ecCodes tests now pass

  • Simplify the xx_new_from_file calls

  • Fix for grib_set_string_array

  • Use ECCODES_DIR to locate the library

  • Remove the new-style high-level interface. It is still available in cfgrib.

0.9.1 (2019-06-06)

  • codes_get_long_array and codes_get_double_array now return a np.ndarray. See: #3.

0.9.0 (2019-05-07)

  • Declare the project as Beta.

0.8.0 (2019-04-08)

  • First public release.

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