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340 changes: 340 additions & 0 deletions doc/source/user_guide/tutorials/data_structures/collections.rst
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.. _ref_tutorials_collections:

===============
DPF Collections
===============

.. include:: ../../links_and_refs.rst

This tutorial shows how to create and work with some DPF collections: FieldsContainer, MeshesContainer and ScopingsContainer.

DPF collections are homogeneous groups of labeled raw data storage structures that allow you to organize and manipulate related data efficiently. Collections are essential for handling multiple time steps, frequency sets, or other labeled datasets in your analysis workflows.

:jupyter-download-script:`Download tutorial as Python script<collections>`
:jupyter-download-notebook:`Download tutorial as Jupyter notebook<collections>`

Introduction to Collections
---------------------------

Collections in DPF serve as containers that group related objects with labels. The main collection types are:

- |FieldsContainer|: A collection of |Field| objects, typically representing results over multiple time steps or frequency sets
- |MeshesContainer|: A collection of |MeshedRegion| objects for different configurations or time steps
- |ScopingsContainer|: A collection of |Scoping| objects for organizing entity selections

Each collection provides methods to:

- Add, retrieve, and iterate over contained objects
- Access objects by label (time, frequency, set ID, etc.)
- Perform operations across all contained objects

Set up the Analysis
-------------------

First, we import the required modules and load a transient analysis result file that contains multiple time steps.

.. jupyter-execute::

# Import the ansys.dpf.core module
import ansys.dpf.core as dpf

# Import the examples module
from ansys.dpf.core import examples

# Load a transient analysis with multiple time steps
result_file_path = examples.find_msup_transient()

# Create a DataSources object
data_sources = dpf.DataSources(result_path=result_file_path)

# Create a Model from the data sources
model = dpf.Model(data_sources=data_sources)

# Display basic model information
print(f"Number of time steps: {len(model.metadata.time_freq_support.time_frequencies)}")
print(f"Available results: {list(model.metadata.result_info.available_results.keys())}")

Working with FieldsContainer
-----------------------------

A |FieldsContainer| is the most commonly used collection in DPF. It stores multiple |Field| objects, each associated with a label such as time step or frequency.

Extract Results into a FieldsContainer
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Let's extract displacement results for all time steps, which will automatically create a |FieldsContainer|.

.. jupyter-execute::

# Get displacement results for all time steps
displacement_fc = model.results.displacement.eval()

# Display FieldsContainer information
print(f"Type: {type(displacement_fc)}")
print(f"Number of fields: {len(displacement_fc)}")
print(f"Labels: {displacement_fc.get_labels()}")
print(f"Available time sets: {list(displacement_fc.get_label_space(0).keys())}")

Access Individual Fields in the Container
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You can access individual fields by their label or index.

.. jupyter-execute::

# Access field by index (first time step)
first_field = displacement_fc[0]
print(f"First field info:")
print(f" Location: {first_field.location}")
print(f" Number of entities: {first_field.scoping.size}")
print(f" Components: {first_field.component_count}")

# Access field by label (specific time step)
time_sets = list(displacement_fc.get_label_space(0).keys())
if len(time_sets) > 1:
second_time_field = displacement_fc.get_field({"time": time_sets[1]})
print(f"\nSecond time step field:")
print(f" Time set: {time_sets[1]}")
print(f" Max displacement magnitude: {max(second_time_field.data):.6f}")

Create a Custom FieldsContainer
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You can create your own |FieldsContainer| and add fields with custom labels.

.. jupyter-execute::

# Create an empty FieldsContainer
custom_fc = dpf.FieldsContainer()

# Set up labels for the container
custom_fc.labels = ["time", "zone"]

# Create sample fields for different time steps and zones
for time_step in [1, 2]:
for zone in [1, 2]:
# Create a simple field with sample data
field = dpf.Field(location=dpf.locations.nodal, nature=dpf.natures.scalar)

# Add some sample nodes and data
field.scoping.ids = [1, 2, 3, 4, 5]
field.data = [float(time_step * zone * i) for i in range(1, 6)]

# Add field to container with labels
custom_fc.add_field({"time": time_step, "zone": zone}, field)

# Display the custom FieldsContainer
print(f"Custom FieldsContainer:")
print(f" Number of fields: {len(custom_fc)}")
print(f" Labels: {custom_fc.labels}")
print(f" Label space: {custom_fc.get_label_space()}")

Working with ScopingsContainer
------------------------------

A |ScopingsContainer| holds multiple |Scoping| objects, which define sets of entity IDs (nodes, elements, etc.).

Create and Populate a ScopingsContainer
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Let's create different node selections and organize them in a |ScopingsContainer|.

.. jupyter-execute::

# Get the mesh from our model
mesh = model.metadata.meshed_region

# Create a ScopingsContainer
scopings_container = dpf.ScopingsContainer()

# Set labels for different selections
scopings_container.labels = ["selection_type"]

# Create different node selections

# Selection 1: First 10 nodes
first_nodes = dpf.Scoping(location=dpf.locations.nodal)
first_nodes.ids = list(range(1, 11))
scopings_container.add_scoping({"selection_type": "first_ten"}, first_nodes)

# Selection 2: Every 10th node (sample)
all_node_ids = mesh.nodes.scoping.ids
every_tenth = dpf.Scoping(location=dpf.locations.nodal)
every_tenth.ids = all_node_ids[::10] # Every 10th node
scopings_container.add_scoping({"selection_type": "every_tenth"}, every_tenth)

# Selection 3: Last 10 nodes
last_nodes = dpf.Scoping(location=dpf.locations.nodal)
last_nodes.ids = all_node_ids[-10:]
scopings_container.add_scoping({"selection_type": "last_ten"}, last_nodes)

# Display ScopingsContainer information
print(f"ScopingsContainer:")
print(f" Number of scopings: {len(scopings_container)}")
print(f" Labels: {scopings_container.labels}")

# Show details of each scoping
for i, scoping in enumerate(scopings_container):
label_space = scopings_container.get_label_space(i)
print(f" Scoping {i}: {label_space} - {scoping.size} entities")

Use ScopingsContainer with Operators
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

|ScopingsContainer| objects can be used with operators to apply operations to multiple selections.

.. jupyter-execute::

# Create an operator to extract displacement on specific node sets
displacement_op = dpf.operators.result.displacement()
displacement_op.inputs.data_sources(data_sources)
displacement_op.inputs.mesh_scoping(scopings_container)

# Evaluate to get results for all scopings
scoped_displacements = displacement_op.eval()

print(f"Displacement results for different node selections:")
print(f" Result type: {type(scoped_displacements)}")
print(f" Number of result fields: {len(scoped_displacements)}")

# Display information for each scoped result
for i, field in enumerate(scoped_displacements):
label_space = scoped_displacements.get_label_space(i)
max_displacement = max(field.data) if len(field.data) > 0 else 0
print(f" Field {i}: {label_space} - {field.scoping.size} nodes, max displacement: {max_displacement:.6f}")

Working with MeshesContainer
----------------------------

A |MeshesContainer| stores multiple |MeshedRegion| objects. This is useful when working with different mesh configurations or time-dependent meshes.

Create a MeshesContainer
^^^^^^^^^^^^^^^^^^^^^^^^

Let's create a |MeshesContainer| with mesh data for different analysis configurations.

.. jupyter-execute::

# Create a MeshesContainer
meshes_container = dpf.MeshesContainer()

# Set labels for different mesh configurations
meshes_container.labels = ["configuration"]

# Get the original mesh
original_mesh = model.metadata.meshed_region

# Add original mesh
meshes_container.add_mesh({"configuration": "original"}, original_mesh)

# Create a modified mesh (example: subset of elements)
# Get element scoping for first half of elements
all_element_ids = original_mesh.elements.scoping.ids
subset_element_ids = all_element_ids[:len(all_element_ids)//2]

# Create element scoping for subset
element_scoping = dpf.Scoping(location=dpf.locations.elemental)
element_scoping.ids = subset_element_ids

# Extract subset mesh using an operator
mesh_extract_op = dpf.operators.mesh.extract_skin()
mesh_extract_op.inputs.mesh(original_mesh)
mesh_extract_op.inputs.element_scoping(element_scoping)
subset_mesh = mesh_extract_op.eval()

# Add subset mesh to container
meshes_container.add_mesh({"configuration": "subset"}, subset_mesh)

# Display MeshesContainer information
print(f"MeshesContainer:")
print(f" Number of meshes: {len(meshes_container)}")
print(f" Labels: {meshes_container.labels}")

# Show details of each mesh
for i, mesh in enumerate(meshes_container):
label_space = meshes_container.get_label_space(i)
print(f" Mesh {i}: {label_space}")
print(f" Nodes: {mesh.nodes.n_nodes}")
print(f" Elements: {mesh.elements.n_elements}")

Collection Operations and Iteration
------------------------------------

Collections support various operations for data manipulation and analysis.

Iterate Through Collections
^^^^^^^^^^^^^^^^^^^^^^^^^^^

You can iterate through collections using different methods.

.. jupyter-execute::

# Iterate through FieldsContainer by index
print("Iterating through displacement fields by index:")
for i in range(min(3, len(displacement_fc))): # Show first 3 fields
field = displacement_fc[i]
label_space = displacement_fc.get_label_space(i)
max_value = max(field.data) if len(field.data) > 0 else 0
print(f" Field {i}: {label_space}, max value: {max_value:.6f}")

print("\nIterating through ScopingsContainer:")
for i, scoping in enumerate(scopings_container):
label_space = scopings_container.get_label_space(i)
print(f" Scoping {i}: {label_space}, size: {scoping.size}")

Filter and Select from Collections
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You can filter collections based on labels or criteria.

.. jupyter-execute::

# Get specific fields from FieldsContainer by label criteria
if len(displacement_fc) >= 2:
# Get the second time step
time_sets = list(displacement_fc.get_label_space(0).keys())
if len(time_sets) > 1:
specific_field = displacement_fc.get_field({"time": time_sets[1]})
print(f"Retrieved field for time {time_sets[1]}:")
print(f" Components: {specific_field.component_count}")
print(f" Location: {specific_field.location}")

# Get scoping by selection criteria
first_ten_scoping = scopings_container.get_scoping({"selection_type": "first_ten"})
print(f"\nRetrieved 'first_ten' scoping:")
print(f" Size: {first_ten_scoping.size}")
print(f" First 5 IDs: {first_ten_scoping.ids[:5]}")

Collection Summary and Best Practices
--------------------------------------

Let's summarize the key concepts and best practices for working with DPF collections.

.. jupyter-execute::

print("DPF Collections Summary:")
print("=" * 50)

print(f"\n1. FieldsContainer:")
print(f" - Purpose: Store multiple Field objects with labels")
print(f" - Common use: Results over time steps, frequencies, or load cases")
print(f" - Example size: {len(displacement_fc)} fields")
print(f" - Labels: {displacement_fc.get_labels()}")

print(f"\n2. ScopingsContainer:")
print(f" - Purpose: Store multiple Scoping objects (entity selections)")
print(f" - Common use: Different node/element selections for analysis")
print(f" - Example size: {len(scopings_container)} scopings")
print(f" - Labels: {scopings_container.labels}")

print(f"\n3. MeshesContainer:")
print(f" - Purpose: Store multiple MeshedRegion objects")
print(f" - Common use: Different mesh configurations or time-dependent meshes")
print(f" - Example size: {len(meshes_container)} meshes")
print(f" - Labels: {meshes_container.labels}")

print(f"\nKey Benefits:")
print(f" - Efficient organization of related data")
print(f" - Label-based access for easy data retrieval")
print(f" - Integration with DPF operators for batch processing")
print(f" - Memory-efficient handling of large datasets")
8 changes: 2 additions & 6 deletions doc/source/user_guide/tutorials/data_structures/index.rst
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Expand Up @@ -29,20 +29,16 @@ These tutorials explains how these structures work and how you can manipulate da


.. grid-item-card:: DPF collections
:link: ref_tutorials_language_and_usage
:link: ref_tutorials_collections
:link-type: ref
:text-align: center
:class-header: sd-bg-light sd-text-dark
:class-footer: sd-bg-light sd-text-dark

This tutorial shows how to create and work with some DPF collections:
FieldsContainer, MeshesContainer and ScopingsContainer

+++
Coming soon

.. toctree::
:maxdepth: 2
:hidden:

data_arrays.rst
collections.rst
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