Python wrapper
===============

Alternatively to using easi directly via cpp code, easi can be used through python wrappers.

Installation
------------

The python wrappers have to first be installed with the ``-DPYTHON_BINDINGS=ON`` cmake option.
Note that ASAGI and ImpalaJIT have to be compiled with ``cmake .. -DCMAKE_CXX_FLAGS="-fPIC"``.
The easi python module can then be found by python when the path to the library (i.e. the path to e.g. easi.cpython-310-x86_64-linux-gnu.so) is added to the $PYTHONPATH environment variable.

.. code-block:: bash

    export PYTHONPATH=your_build_folder/python_bindings:$PYTHONPATH

Use
---

The module can then be used as follows:

.. code-block:: python

    import numpy as np
    import easi

    coords = np.random.rand(10,3)
    region = np.random.randint(1,3, 10)
    print(easi.evaluate_model(coords, region, ["rho", "lambda"], "test.yaml"))

This will print the following dictionary, e.g. for https://github.com/SeisSol/easi/blob/master/examples/1_groups.yaml and regions [2 1 1 2 1 1 1 2 1 1]:

.. code-block:: python

    {'rho': array([2700., 2600., 2600., 2700., 2600., 2600., 2600., 2700., 2600.,
           2600.]), 'lambda': array([3.24038016e+10, 2.08000000e+10, 2.08000000e+10, 3.24038016e+10,
           2.08000000e+10, 2.08000000e+10, 2.08000000e+10, 3.24038016e+10,
           2.08000000e+10, 2.08000000e+10])}

Troubleshooting
---------------

An error ``libnetcdf.so.18: undefined symbol: H5Pset_dxpl_mpio`` at ``import easi`` is probably associated with a module loaded above depending on a conflicting netcdf or hdf5 library (e.g. vtk).

An error ``ModuleNotFoundError: No module named 'easi'`` may be cause by a $PYTHONPATH not pointing to the right folder, or a library compiled with the wrong python version (e.g. the library was compiled for the default python version and used with the Anaconda python, with different version number).