Implement ModalMechanicalSimulation results (#289)

* Add modal_mechanical_simulation.py

* Reorder arguments and docstrings in modal_mechanical_simulation.py

* Fix test_load_simulation.py

* Expose frequencies and modes for Modal results, and take first mode only by default.

* Update all result methods and docstrings accordingly

* Filter results according to list for modal

* Fix (load_steps, sub_steps) logic.

* Add stress tests for modal

* Redirect modes to set_ids for modal

* Test more results for modal

* Add location argument to generic result methods of ModalMechanicalSimulation

* Add location argument to generic result methods of StaticMechanicalSimulation

* Add location argument to generic result methods of TransientMechanicalSimulation

* Add Selection.select_nodes_of_elements

* Allow for several named selections in Selection.select_named_selection

* Fix SpatialSelection.select_nodes_of_elements

* Switch ModalMechanicalSimulation._get_result to using Selection API and workflow.

* Allow for multiple set_ids to correspond to a single "times" or "frequency" value.

* Move set_ids and all_sets to bottom of signatures, update docstrings.

* Swith StaticMechanicalSimulation._get_result and TransientMechanicalSimulation._get_result to using Selection API

* Fix errors due to switch to Selection API

* Fix TimeFreqSelection.select_time_freq_values by setting the field for values as scalar.

* Always use eqv_fc

* Fix Simulation._build_components_from_principal for string input.

* Fix principal step to use invariants_fc. Cannot ask for multiple principal results anymore. The combination logic needs to be defined.

* Update tests to not use EPEL1 and others but instead use the Mechanical-equivalent of invariants_fc

* Initiate DataObjects with an Index

* Initiate DataObjects with an Index

* Fix DataObject init

* Set scoping as output of result workflow to give as index argument ot DataObject

* Add elastic_strain_eqv_von_mises to Transient

* Add elastic_strain_eqv_von_mises to Static

* Add elastic_strain_eqv_von_mises to Modal

* Delay averaging when asking for eqv strain

* Fix setting scoping as output for index of DataObject

src/ansys/dpf/post/common.py

@@ -1,9 +1,7 @@
 """Module containing the common tools for a better usage of the DPF-Post module."""
 
-from ansys.dpf.post.simulation import (
-    HarmonicMechanicalSimulation,
-    ModalMechanicalSimulation,
-)
+from ansys.dpf.post.modal_mechanical_simulation import ModalMechanicalSimulation
+from ansys.dpf.post.simulation import HarmonicMechanicalSimulation
 from ansys.dpf.post.static_mechanical_simulation import StaticMechanicalSimulation
 from ansys.dpf.post.transient_mechanical_simulation import TransientMechanicalSimulation
 

src/ansys/dpf/post/data_object.py

@@ -5,9 +5,7 @@
 class DataObject:
     """Exposes the fields container generated by a result provider."""
 
-    def __init__(
-        self, fields_container=None, server=None, mesh_scoping=None, columns=None
-    ):
+    def __init__(self, fields_container=None, server=None, index=None, columns=None):
         """Wrap a FieldsContainer within a DataObject.
 
         Parameters
@@ -16,17 +14,17 @@ def __init__(
             :class:`ansys.dpf.core.fields_container.FieldsContainer`to wrap.
         server:
             DPF server to use.
-        mesh_scoping:
-            Scoping to use.
+        index:
+            Index to use.
         columns:
             Columns to use.
         """
         self._fc = fields_container
-        if columns:
+        if columns is not None:
             self._columns = columns
 
-        if mesh_scoping:
-            self._mesh_scoping = mesh_scoping
+        if index is not None:
+            self._index = index
 
         # super().__init__(fields_container._internal_obj, server)
 
@@ -93,9 +91,7 @@ def as_data_frame(self, columns=None, **kwargs):
                 "This function requires for the DataObject to contain only"
                 "one data entity."
             )
-        df = pd.DataFrame(
-            self.as_array(), columns=columns, index=self._mesh_scoping.ids
-        )
+        df = pd.DataFrame(self.as_array(), columns=columns, index=self._index)
         df.name = self._fc[-1].name
         return df