handle PEtab v2 + multilanguage

petab/problem.py

@@ -217,10 +217,12 @@ def from_yaml(yaml_config: Union[Dict, Path, str]) -> 'Problem':
                              'Consider using '
                              'petab.CompositeProblem.from_yaml() instead.')
 
-        if yaml_config[FORMAT_VERSION] != format_version.__format_version__:
-            raise ValueError("Provided PEtab files are of unsupported version"
+        if yaml_config[FORMAT_VERSION] not in {"1", 1, "1.0.0", "2.0.0"}:
+            raise ValueError("Provided PEtab files are of unsupported version "
                              f"{yaml_config[FORMAT_VERSION]}. Expected "
                              f"{format_version.__format_version__}.")
+        if yaml_config[FORMAT_VERSION] == "2.0.0":
+            warn("Support for PEtab2.0 is experimental!")
 
         problem0 = yaml_config['problems'][0]
 
@@ -248,11 +250,14 @@ def from_yaml(yaml_config: Union[Dict, Path, str]) -> 'Problem':
                 # TODO https://github.com/PEtab-dev/libpetab-python/issues/6
                 raise NotImplementedError(
                     'Support for multiple models is not yet implemented.')
-            model_id, model_info = next(iter(problem0[MODEL_FILES].items()))
-            model = model_factory(get_path(model_info[MODEL_LOCATION]),
-                                  model_info[MODEL_LANGUAGE],
-                                  model_id=model_id) \
-                if problem0[SBML_FILES] else None
+            if not problem0[MODEL_FILES]:
+                model = None
+            else:
+                model_id, model_info = \
+                    next(iter(problem0[MODEL_FILES].items()))
+                model = model_factory(get_path(model_info[MODEL_LOCATION]),
+                                      model_info[MODEL_LANGUAGE],
+                                      model_id=model_id)
 
         measurement_files = [
             get_path(f) for f in problem0.get(MEASUREMENT_FILES, [])]