Python (PICMI)¶
WarpX uses the PICMI standard for its Python input files. See PICMI information and source code.
WarpX can be run in one of two modes. It can run as a preprocessor, using the Python input file to generate an input file to be used by the C++ version, or it can be run directly from Python.
In either mode, if using a virtual environment, be sure to activate it before compiling and running WarpX.
Example input files can be found in the examples section. The examples support running in both modes by commenting and uncommenting the appropriate lines.
WarpX requires Python version 3.6 or newer.
Using Python input as a preprocessor¶
In this case, only the pure Python version needs to be installed, as described here.
In order to run a new simulation:
Create a new directory, where the simulation will be run.
Add a Python script in the directory.
The input file should have the line like sim.write_input_file(file_name = 'inputs_from_PICMI')
which runs the preprocessor, generating the AMReX inputs file.
Run the script with Python:
python <python_script>
where <python_script> is the name of the script.
This creates the WarpX input file that you can run as normal with the WarpX executable.
Running WarpX directly from Python¶
For this, a full Python installation of WarpX is required, as described in the install documentation (developers).
In order to run a new simulation:
Create a new directory, where the simulation will be run.
Add a Python script in the directory.
The input file should have the line sim.step() which runs the simulation.
Run the script with Python:
mpirun -np <n_ranks> python <python_script>
where <n_ranks> is the number of MPI ranks used, and <python_script>
is the name of the script.