Operators overview

In DPF, operators provide the primary method for interacting with and extracting results. Within DPF-Core, operators are directly exposed with the Operators class as well as wrapped within several other convenience classes.

For a list of all operators, see Operators.

This example demonstrates how to work directly with operators and compares this method to a wrapped approach.

# Import the necessary modules
from ansys.dpf import core as dpf
from ansys.dpf.core import examples

Create a model object to establish a connection with an example result file:

model = dpf.Model(examples.find_static_rst())
print(model)

DPF Model
------------------------------
Static analysis
Unit system: MKS: m, kg, N, s, V, A, degC
Physics Type: Mechanical
Available results:
     -  displacement: Nodal Displacement
     -  reaction_force: Nodal Force
     -  stress: ElementalNodal Stress
     -  elemental_volume: Elemental Volume
     -  stiffness_matrix_energy: Elemental Energy-stiffness matrix
     -  artificial_hourglass_energy: Elemental Hourglass Energy
     -  thermal_dissipation_energy: Elemental thermal dissipation energy
     -  kinetic_energy: Elemental Kinetic Energy
     -  co_energy: Elemental co-energy
     -  incremental_energy: Elemental incremental energy
     -  elastic_strain: ElementalNodal Strain
     -  element_euler_angles: ElementalNodal Element Euler Angles
     -  structural_temperature: ElementalNodal Structural temperature
------------------------------
DPF  Meshed Region:
  81 nodes
  8 elements
  Unit: m
  With solid (3D) elements
------------------------------
DPF  Time/Freq Support:
  Number of sets: 1
Cumulative     Time (s)       LoadStep       Substep
1              1.000000       1              1

Next, create a raw displacement operator "U". Each operator contains input and output pins that can be connected to various sources to include other operators. This allows operators to be “chained” to allow for highly efficient operations.

To print out the available inputs and outputs of the displacement operator:

disp_op = dpf.Operator("U")
print(disp_op.inputs)
print(disp_op.outputs)

Available inputs:
     -   time_scoping : Scoping, int, list, float, Field, optional
         Time/freq values (use doubles or field), time/freq set ids (use ints
         or scoping) or time/freq step ids (use scoping with timefreq_steps
         location) required in output. to specify time/freq values at specific
         load steps, put a field (and not a list) in input with a scoping
         located on "timefreq_steps". linear time freq intrapolation is
         performed if the values are not in the result files and the data at
         the max time or freq is taken when time/freqs are higher than
         available time/freqs in result files.

     -   mesh_scoping : ScopingsContainer, Scoping, optional
         Nodes or elements scoping required in output. the output fields will
         be scoped on these node or element ids. to figure out the ordering of
         the fields data, look at their scoping ids as they might not be
         ordered as the input scoping was. the scoping's location indicates
         whether nodes or elements are asked for. using scopings container
         allows you to split the result fields container into domains

     -   fields_container : FieldsContainer, optional
         Fields container already allocated modified inplace

     -   streams_container : StreamsContainer, optional
         Result file container allowed to be kept open to cache data

     -   data_sources : DataSources
         Result file path container, used if no streams are set

     -   bool_rotate_to_global : bool, optional
         If true the field is rotated to global coordinate system (default
         true)

     -   mesh : MeshedRegion, MeshesContainer, optional
         Prevents from reading the mesh in the result files

     -   read_cyclic : Enum Dataprocessing::Ecyclicreading, int, optional
         If 0 cyclic symmetry is ignored, if 1 cyclic sector is read, if 2
         cyclic expansion is done, if 3 cyclic expansion is done and stages are
         merged (default is 1)


Available outputs:
     -   fields_container

Compute the maximum normalized displacement

This example demonstrate how to chain various operators. It connects the input of the operator to the data sources contained within the model object and then the maximum of the norm of the operator.

# Connect to the data sources of the model.
disp_op.inputs.data_sources.connect(model.metadata.data_sources)

# Create a fields container norm operator and connect it to the
# displacement operator to chain the operators.
norm_op = dpf.Operator("norm_fc")
norm_op.inputs.connect(disp_op.outputs)

# Create a fields container min/max operator and connect it to the
# output of the norm operator.
mm_op = dpf.Operator("min_max_fc")
mm_op.inputs.connect(norm_op.outputs)

# Finally, get the value of the maximum displacement.
field_max = mm_op.outputs.field_max()
print(field_max)
print(field_max.data)

DPF displacement_1.s Field
  Location: Nodal
  Unit: m
  1 entities
  Data: 1 components and 1 elementary data

  IDs                   data(m)
  ------------          ----------
  0                     1.481537e-08



[1.48153706e-08]

Wrapped operators

The model.results property contains all the wrapped operators available for a given result. This is provided out of convenience because all operators may not be available for a given result. Consequently, it is much easier to reference available operators by first running:

print(model.results)

Static analysis
Unit system: MKS: m, kg, N, s, V, A, degC
Physics Type: Mechanical
Available results:
     -  displacement: Nodal Displacement
     -  reaction_force: Nodal Force
     -  stress: ElementalNodal Stress
     -  elemental_volume: Elemental Volume
     -  stiffness_matrix_energy: Elemental Energy-stiffness matrix
     -  artificial_hourglass_energy: Elemental Hourglass Energy
     -  thermal_dissipation_energy: Elemental thermal dissipation energy
     -  kinetic_energy: Elemental Kinetic Energy
     -  co_energy: Elemental co-energy
     -  incremental_energy: Elemental incremental energy
     -  elastic_strain: ElementalNodal Strain
     -  element_euler_angles: ElementalNodal Element Euler Angles
     -  structural_temperature: ElementalNodal Structural temperature

Create the displacement operator directly from the results property:

disp_op = model.results.displacement()

# Out of convenience, the ``operators`` module contains available operators.
# These operators can be chained to create a workflow in one line.
from ansys.dpf.core import operators

mm_op = operators.min_max.min_max_fc(operators.math.norm_fc(disp_op))

# Finally, get the value of the maximum displacement.
field_max = mm_op.outputs.field_max()
print(field_max)
print(field_max.data)

DPF displacement_1.s Field
  Location: Nodal
  Unit: m
  1 entities
  Data: 1 components and 1 elementary data

  IDs                   data(m)
  ------------          ----------
  0                     1.481537e-08



[1.48153706e-08]

Plot the displacement:

print(model.metadata.meshed_region.plot(disp_op.outputs.fields_container()))

None

Scripting operator syntax

Because DPF provides a scripting syntax, knowing an operator’s “string name” is not mandatory. While this example is similar to the above script, it uses the DPF scripting syntax.

Instead of using a model class instance, use a DdataSources object directly. The DataSources constructor input is a path.

ds = dpf.DataSources(examples.find_static_rst())
print(examples.find_static_rst())

C:\hostedtoolcache\windows\Python\3.9.13\x64\lib\site-packages\ansys\dpf\core\examples\result_files\static.rst

Instantiate the operators and connect them:

disp_op = dpf.operators.result.displacement()
disp_op.inputs.data_sources.connect(ds)
norm_op = dpf.operators.math.norm_fc()
norm_op.inputs.connect(disp_op.outputs)
mm_op = dpf.operators.min_max.min_max_fc()
mm_op.inputs.connect(norm_op.outputs)

Get the output and print the result data:

field_max = mm_op.outputs.field_max()
print(field_max.data)

[1.48153706e-08]