Creating yMMSL from Python

yMMSL files are YAML files, and yMMSL is usually written in YAML. In fact, even if you want to create a yMMSL configuration in Python, it’s often convenient to just embed a string containing a YAML description and converting it to objects using ymmsl.load().

However, all the classes mentioned here are normal Python classes. They have constructors which you can use to create instances, and their attributes can be changed as needed.

This example shows creating a yMMSL configuration in Python and saving it to a file.

Creating a Configuration and saving it (docs/from_python.py)

from pathlib import Path
from ymmsl.v0_2 import (
        Component, Conduit, Configuration, ExecutionModel, Model, MPICoresResReq, Ports,
        Program, ThreadedResReq)
from ymmsl import save

components = [
    Component(
            'macro', Ports(o_i='out', s='in'), 'Macro model',
            implementation='macro_model'),
    Component(
            'micro', Ports(f_init='in', o_f='out'), 'Micro model',
            implementation='micro_model')]

conduits = [
    Conduit('macro.out', 'micro.in'),
    Conduit('micro.out', 'macro.in')]

model = Model(
        'my_model', description='Example model created in Python',
        components=components, conduits=conduits)

programs = [
    Program(
        'macro_model', description='Program implementing the macro model',
        executable='/home/user/model'),
    Program(
        'micro_model', description='Micro model program',
        modules='GCC/14.1.0 OpenMPI/5.0.3',
        execution_model=ExecutionModel.OPENMPI, executable='/home/user/model2')]

resources = [
    ThreadedResReq('macro', 1),
    MPICoresResReq('micro', 8)]

config = Configuration(
        'Example configuration', models=[model], programs=programs,
        resources=resources)

save(config, Path('out.ymmsl'))

This will output:

Output of from_python.py (docs/from_python.ymmsl)

ymmsl_version: v0.2
description: |
  Example configuration
models:
  my_model:
    description: |
      Example model created in Python
    components:
      macro:
        ports:
          o_i: out
          s: in
        description: |
          Macro model
        implementation: macro_model
      micro:
        ports:
          f_init: in
          o_f: out
        description: |
          Micro model
        implementation: micro_model
    conduits:
      macro.out: micro.in
      micro.out: macro.in
programs:
  macro_model:
    description: |
      Program implementing the macro model
    executable: /home/user/model
  micro_model:
    description: |
      Micro model program
    modules:
    - GCC/14.1.0
    - OpenMPI/5.0.3
    execution_model: openmpi
    executable: /home/user/model2
resources:
  macro:
    threads: 1
  micro:
    mpi_processes: 8

Another use case is loading a yMMSL file and modifying it:

Loading, modifying, and saving a yMMSL file (docs/load_modify_save.py)

from pathlib import Path
import ymmsl

config = ymmsl.load(Path('from_python.ymmsl'))

config.settings['d'] = 0.12

ymmsl.save(config, Path('out.ymmsl'))

For more details about these classes and what you can do with them, we refer to the API documentation.