Installation#

Requirements#

Build Dependencies#

Dependency	Link
CMake	http://www.cmake.org/
ecbuild	ecmwf/ecbuild
Pybind11	https://pybind11.readthedocs.io

Runtime Dependencies#

Dependency	Link
metkit	ecmwf/metkit
eckit	ecmwf/eckit
eccodes	ecmwf/eccodes

eccodes is optional. The CLI reports it as [Optional] and a missing eccodes does not cause a non-zero exit.

Python Dependencies#

pymetkit requires Python >= 3.11. The runtime dependencies are pinned in python/requirements.txt:

uv pip install -r python/requirements.txt

python/requirements-build.txt additionally covers everything needed to build the documentation and run the doctests.

Build from sources (recommended)#

PyMetKit is built as part of metkit by enabling the ENABLE_PYTHON_METKIT_INTERFACE CMake option, which requires Python >= 3.11 and pybind11 >= 3.0.1.

Configure and build metkit (with its dependencies already installed at <prefix>):

cmake -B build -S . -G Ninja \
      -DCMAKE_PREFIX_PATH=<prefix> \
      -DCMAKE_BUILD_TYPE=RelWithDebInfo \
      -DENABLE_PYTHON_METKIT_INTERFACE=ON
cmake --build build -j

This produces the pymetkit wheel in the build directory and a ready-to-use package layout under build/pymetkit-python-package-staging.

Tip

For local exploration you can put the staging directory on your PYTHONPATH instead of installing the wheel:

export PYTHONPATH=<path-to-build>/pymetkit-python-package-staging

Run the tests to verify the build:

cd build
ctest --output-on-failure -L pymetkit

Installation via PyPI#

uv venv
source .venv/bin/activate
uv pip install pymetkit

Set the METKIT_HOME environment variable so findlibs can locate the library:

export METKIT_HOME=<path_to_metkit_home>

Diagnosing Library Resolution#

PyMetKit uses findlibs to locate the metkit shared library and its runtime dependencies at import time. If you encounter errors caused by the wrong library version being loaded, the built-in CLI can help you inspect what findlibs resolves on your system.

Print the installation root of the metkit library:

python -m pymetkit --print-home

Print the resolved home directories for all runtime dependencies (eckit, eccodes, metkit), together with any active FINDLIBS_DISABLE_* environment variables that suppress specific search paths:

python -m pymetkit --print-home-deps

Add -v / --verbose to either command to raise the log level from INFO to DEBUG.

ERROR lines indicate dependencies findlibs could not locate — set the corresponding <LIBNAME>_HOME environment variable to resolve them explicitly.

The exit code tells you whether the resolution succeeded:

Exit code	Meaning
0	All required dependencies resolved. A missing optional dependency (`eccodes`) still exits `0`.
1	A required dependency could not be located.
2	No flag given; the help text is printed instead.