YetAnotherCoupler 3.0.3
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The Python bindings (yac.pyx)

Table of Contents

For a module reference see yac.

This package provides python bindings for the YAC coupler. They are generated using cython and can be enabled with the --enable-python-bindings configure flag. This enables the configure checks, the compilation of the python extension module (.so file) and the corresponding tests. Hard dependencies for the python bindings are the packages

  • cython
  • numpy

For the test suite also matplotlib are recommended. For the function Component.comp_comm and get_comps_comm the module mpi4py is required. mpi4py must be compiled with the same MPI version as YAC to function properly. To convert the iso8601 date/time strings returned by YAC functions, e.g. YAC.start_datetime to a python datetime format we recommend isodate or the pythonbindings of mtime. All packages (except for mtime) can be installed by pip.

To use the python bindings in a python program, add the path containing the python extension module file to the PYTHONPATH environment variable. Alternatively, you can install the extension module by executing python install in the python sub-directory of your build directory.

The bindings are designed to build a thin layer between python and yac. I.e. methods are directly forwarded to the corresponding yac functions with a few exceptions:

  • For all data structures for that yac returns an id, python creates an object that holds this id and provides member functions that use this id.
  • Whenever a c-pointer to memory is expected by the yac function, the argument of the python function is converted to a contiguous numpy array using numpy.ascontiguousarray (involving a copy if it is not already contiguous) and converted to a cython memory view to extract the size and pointer.
  • MPI communicators are converted into mpi4py.MPI.Comm and vice-versa.

Python Examples

In the examples directory a framework of classes can be found that act as model component. To start a configuration with different components the can be used. It allows sequential coupling as well as parallel coupling.

The framework contains the following example components: