============ Installation ============ ------------ Requirements ------------ The following packages are *required* to work with ESMPy: * `ESMF installation `_ * `python `_, minimum version 3.7 * `numpy `_ The following packages are *optional*: * ESMF installation with NetCDF - required to create :class:`Grids ` and :class:`Meshes ` from file - NetCDF must be built as a shared library for ESMPy installation to succeed * `mpi4py `_- python bindings to MPI, needed to run some of the parallel regridding examples * `pytest `_ - for testing ---------------- Getting the code ---------------- The ESMPy source code can be downloaded from the `ESMF git repository `_. The `ESMF User's Guide `_ contains information on building and installing esmpy. The `ESMF Reference Manual `_ contains information on the architecture of ESMF, example code, and details of the API (Application Programming Interface). ~~~~~~~~~~~~~~~~~ Anaconda Packages ~~~~~~~~~~~~~~~~~ ESMPy conda packages are available through the conda-forge channel: .. code:: conda create -n esmpy -c conda-forge esmpy Specific versions of the conda package can be installed like this: .. code:: conda create -n esmpy -c conda-forge esmpy=8.1.0 Development versions can be found in the ``esmpy_dev`` channel: .. code:: conda create -n esmpy -c conda-forge -c esmpy_dev esmpy ---------------------------- Installing ESMPy from Source ---------------------------- When installing from source, ESMPy uses `pip `_ to build and install the package. This requires setting an environment variable pointing to a file named esmf.mk that is generated during an ESMF installation. The path of this file is: .. code:: /lib/libO>//esmf.mk An installation of ESMPy in the default location for Python packages can be done with the following command issued from the top level ESMPy directory: .. code:: python3 -m pip install . Please contact esmf_support@ucar.edu with any questions. .. Note:: With some python versions, there is a problem with the automatic installation of the required package ``setuptools-git-versioning``. If the output from the ``pip install`` command ends with ``Successfully installed esmpy-0.0.0``, this indicates that the ``setuptools-git-versioning`` package was not invoked and the build thinks you are using ESMF version 0.0.0. This will cause problems when you try to use ESMPy. To solve this problem, simply rerun the above installation command (``python3 -m pip install .``). You should then see a reasonable version number at the end, such as, ``Successfully installed esmpy-8.4.0``. --------------- Importing ESMPy --------------- To use ESMPy in an external program, import it with: .. code:: import esmpy The environment variable ``ESMFMKFILE`` must be set when to use ESMPy. ---------- Validation ---------- The ESMPy testing is done with the pytest package, both in serial and parallel. Basic unit tests can be run with the following command: .. code:: python3 -m pytest There are a few other pytest targets available for a wider range of testing if greater test coverage is desired: .. code:: make test_unit make test_examples make test_unit_parallel make test_examples_parallel make test_regrid_from_file .. Note:: The ``regrid_from_file`` and ``example`` tests can take up a lot of memory and bandwidth. The ``download_regrid_from_file`` and ``download_examples`` commands will simply download the test files without actually running them (allowing the stress on the machine to be applied to bandwidth first, and then memory). ----------- Limitations ----------- ESMPy doesn't include many aspects of ESMF, including components, field bundles, time management, etc. The limitations listed here are relative to ESMF offline and integrated regridding capabilities. - ESMPy cannot use an ESMF installation that is built with external LAPACK support. - Coordinates cannot be retrieved from the elements of a :class:`~esmpy.api.mesh.Mesh`. This can affect the ability to set :class:`~esmpy.api.field.Field` values on a source :class:`~esmpy.api.mesh.Mesh` created from file when using conservative regridding. - Multi-tile :class:`~esmpy.api.grid.Grid` support is limited to cubed-sphere grids created on 6 processors. A cubed-sphere grid can be created on any number of processors, but only when it is created on 6 processors will the coordinates be retrievable for the entire object. A :class:`~esmpy.api.field.Field` created from a cubed-sphere :class:`~esmpy.api.grid.Grid` cannot be written to file in parallel. - There is no ``FieldBundle`` class, only single :class:`Fields `. Testing related: - Nightly regression testing is limited to a small subset of the ESMF test platforms, including Darwin and Linux running gfortran with openMPI.