monai.deploy.operators.DICOMDataLoaderOperator

class monai.deploy.operators.DICOMDataLoaderOperator(fragment, *args, input_folder=PosixPath('/home/docs/checkouts/readthedocs.org/user_builds/monai-deploy-app-sdk/checkouts/3.4.0/docs/source/input'), output_name='dicom_study_list', must_load=True, **kwargs)

Bases: Operator

This operator loads DICOM studies into memory from a folder of DICOM instance files.

Named Input:

input_folder: Path to the folder containing DICOM instance files. Optional and not requiring input.

If present, data from this input will be used as the input folder of DICOM instance files.

Name Output:

dicom_study_list: A list of DICOMStudy objects in memory. The name can be changed via attribute, output_name.

Creates an instance of this class.

Parameters:

• fragment (Fragment) – An instance of the Application class which is derived from Fragment.

• input_folder (Path) – Folder containing DICOM instance files to load from. Defaults to input in the current working directory. Can be overridden by via the named input receiving from other’s output.

• output_name (str) – The name for the output, which is list of DICOMStudy objects. Defaults to dicom_study_list, and if None or blank passed in.

• must_load (bool) – If true, raise exception if no study is loaded. Defaults to True.

Methods

__init__(fragment, *args[, input_folder, ...])	Creates an instance of this class.
add_arg(*args, **kwargs)	Overloaded function.
add_dynamic_flow(*args, **kwargs)	Overloaded function.
compute(op_input, op_output, context)	Performs computation for this operator and handlesI/O.
enable_metadata(self, enable)	Configure whether or not the metadata feature is enabled for this operator.
find_all_flow_info(self, predicate)	Find all flow info objects in the operator's next flows that match a given condition.
find_flow_info(self, predicate)	Find a flow info in the operator's next flows based on a given predicate.
initialize()	Default implementation of initialize
load_data_to_studies(input_path)	Load DICOM data from files into DICOMStudy objects in a list.
populate_series_attributes(series, sop_instance)	Populates series level attributes in the study data structure.
populate_study_attributes(study, sop_instance)	Populates study level attributes in the study data structure.
queue_policy(self, port_name, port_type, policy)	Set the queue policy to be used by an input (or output) port's receiver (or transmitter).
receiver(self, port_name)	Get the receiver used by an input port.
resource(self, name)	Resources associated with the operator.
service(self, service_type[, id])	Retrieve a registered fragment service through the component's fragment.
setup(spec)	Default implementation of setup method.
start()	Default implementation of start
stop()	Default implementation of stop
stop_execution(self)	Stop the execution of the operator.
transmitter(self, port_name)	Get the transmitter used by an output port.

Attributes

DEFAULT_INPUT_FOLDER
DEFAULT_OUTPUT_NAME
INPUT_EXEC_PORT_NAME
OUTPUT_EXEC_PORT_NAME
SOP_CLASSES_TO_IGNORE
args	The list of arguments associated with the component.
async_condition	The internal asynchronous condition for the operator.
conditions	Conditions associated with the operator.
description	YAML formatted string describing the operator.
execution_context	The execution context for the operator.
fragment	The fragment (holoscan.core.Fragment) that the operator belongs to.
id	The identifier of the component.
is_metadata_enabled	Boolean indicating whether the fragment this operator belongs to has metadata transmission enabled.
metadata	The metadata dictionary (holoscan.core.MetadataDictionary) associated with the operator.
metadata_policy	The metadata policy (holoscan.core.MetadataPolicy) associated with the operator.
name	The name of the operator.
next_flows	Get the list of flow information for connections to downstream operators.
operator_type	The operator type.
resources	Resources associated with the operator.
spec	The operator spec (holoscan.core.OperatorSpec) associated with the operator.

class OperatorType(self: holoscan.core._core.OperatorBase.OperatorType, value: int)

Bases: pybind11_object

Enum class for operator types used by the executor.

• NATIVE: Native operator.

• GXF: GXF operator.

• VIRTUAL: Virtual operator. (for internal use, not intended for use by application authors)

Members:

NATIVE

GXF

VIRTUAL

property name

__init__(fragment, *args, input_folder=PosixPath('/home/docs/checkouts/readthedocs.org/user_builds/monai-deploy-app-sdk/checkouts/3.4.0/docs/source/input'), output_name='dicom_study_list', must_load=True, **kwargs)

Creates an instance of this class.

Parameters:

• fragment (Fragment) – An instance of the Application class which is derived from Fragment.

• input_folder (Path) – Folder containing DICOM instance files to load from. Defaults to input in the current working directory. Can be overridden by via the named input receiving from other’s output.

• output_name (str) – The name for the output, which is list of DICOMStudy objects. Defaults to dicom_study_list, and if None or blank passed in.

• must_load (bool) – If true, raise exception if no study is loaded. Defaults to True.

add_arg(*args, **kwargs)

Overloaded function.

1. add_arg(self: holoscan.core._core.OperatorBase, arg: holoscan.core._core.Arg) -> None

Add an argument to the component.

2. add_arg(self: holoscan.core._core.OperatorBase, arg: holoscan.core._core.ArgList) -> None

Add a list of arguments to the component.

3. add_arg(self: holoscan.core._core.OperatorBase, **kwargs) -> None

Add arguments to the component via Python kwargs.

4. add_arg(self: holoscan.core._core.OperatorBase, arg: holoscan.core._core.ConditionBase) -> None

5. add_arg(self: holoscan.core._core.OperatorBase, arg: holoscan.core._core.ResourceBase) -> None

Add a condition or resource to the Operator.

This can be used to add a condition or resource to an operator after it has already been constructed.

Parameters

argholoscan.core.Condition or holoscan.core.Resource

The condition or resource to add.

add_dynamic_flow(*args, **kwargs)

Overloaded function.

1. add_dynamic_flow(self: holoscan.core._core.OperatorBase, flow: holoscan.core._core.FlowInfo) -> None

2. add_dynamic_flow(self: holoscan.core._core.OperatorBase, flows: list[holoscan.core._core.FlowInfo]) -> None

3. add_dynamic_flow(self: holoscan.core._core.OperatorBase, next_op: holoscan.core._core.OperatorBase, next_input_port_name: str = ‘’) -> None

Add a dynamic flow from this operator to another operator.

Parameters

next_opholoscan.core.Operator

The downstream operator to connect to.

next_input_port_namestr, optional

The name of the input port on the downstream operator to connect to. If not specified, the first available input port will be used.

Notes

This method has several overloads to support different ways of creating dynamic flows:

1. add_dynamic_flow(next_op: Operator, next_input_port_name: str = ‘’) - Basic connection using default output port. This is the simplest form for connecting

   two operators when you only need to specify the destination.

2. add_dynamic_flow(curr_output_port_name: str, next_op: Operator, next_input_port_name: str = ‘’) - Connection with explicit output port specification. Use this when the source operator has

   multiple output ports and you need to specify which one to use.

3. add_dynamic_flow(flow: FlowInfo) - Connection using a FlowInfo object, which encapsulates all connection details including:

   • Source operator and its output port specification

   • Destination operator and its input port specification

   • Port names and associated IOSpecs

   • This is useful for complex connections or when reusing connection patterns.

4. add_dynamic_flow(flows: List[FlowInfo]) - Batch connection using multiple FlowInfo objects. Use this to set up multiple

   connections in a single call, which is more efficient than making multiple individual connections.

The FlowInfo class provides a complete description of a flow connection between operators, including all port specifications and naming. It’s particularly useful when you need to:

• Store and reuse connection patterns

• Create complex routing configurations

• Handle dynamic port specifications

• Manage multiple connections systematically

4. add_dynamic_flow(self: holoscan.core._core.OperatorBase, curr_output_port_name: str, next_op: holoscan.core._core.OperatorBase, next_input_port_name: str = ‘’) -> None

property args

The list of arguments associated with the component.

Returns

arglist : holoscan.core.ArgList

property async_condition

The internal asynchronous condition for the operator.

This property provides access to the internal asynchronous condition for the operator, which controls the scheduling of the operator’s compute method.

Returns

conditionholoscan.conditions.AsynchronousCondition

An instance of holoscan.conditions.AsynchronousCondition that is the internal asynchronous condition for the operator.

Notes

This object is only accessible after the executor has called Operator.initialize() via run() or run_async(). If accessed during Application.compose(), it will return None.

compute(op_input, op_output, context)

Performs computation for this operator and handlesI/O.

property conditions

Conditions associated with the operator.

property description

YAML formatted string describing the operator.

enable_metadata(self: holoscan.core._core.OperatorBase, enable: bool) → None

Configure whether or not the metadata feature is enabled for this operator. If it is not set, the default value will be determined by the enable_metadata setting from the Fragment that this operator belongs to.

property execution_context

The execution context for the operator.

This property provides access to the execution context of the operator, which contains information about the current execution environment including scheduling details.

Returns

holoscan.core.ExecutionContext

The execution context object for this operator.

find_all_flow_info(self: holoscan.core._core.OperatorBase, predicate: Callable[[holoscan.core._core.FlowInfo], bool]) → list[holoscan.core._core.FlowInfo]

Find all flow info objects in the operator’s next flows that match a given condition.

Parameters

predicatecallable

A function that takes a FlowInfo object and returns a boolean.

Returns

list[holoscan.core.FlowInfo]

List of matching FlowInfo objects.

find_flow_info(self: holoscan.core._core.OperatorBase, predicate: Callable[[holoscan.core._core.FlowInfo], bool]) → holoscan.core._core.FlowInfo

Find a flow info in the operator’s next flows based on a given predicate.

Parameters

predicatecallable

A function that takes a FlowInfo object and returns a boolean.

Returns

holoscan.core.FlowInfo or None

The first matching FlowInfo object, or None if not found.

property fragment

The fragment (holoscan.core.Fragment) that the operator belongs to.

property id

The identifier of the component.

The identifier is initially set to -1, and will become a valid value when the component is initialized.

With the default executor (holoscan.gxf.GXFExecutor), the identifier is set to the GXF component ID.

Returns

id : int

initialize()

Default implementation of initialize

property is_metadata_enabled

Boolean indicating whether the fragment this operator belongs to has metadata transmission enabled.

load_data_to_studies(input_path)

Load DICOM data from files into DICOMStudy objects in a list.

It scans through the input directory for all SOP instances. It groups them by a collection of studies where each study contains one or more series. This method returns a list of studies. If there is no studies loaded, an exception will be thrown if set to must load.

Parameters:

input_path (Path) – The folder containing DICOM instance files.

Returns:

List of DICOMStudy.

Return type:

List[DICOMStudy]

Raises:

• ValueError – If the folder to load files from does not exist.

• ItemNotExistsError – If no studies loaded and must_load is True.

property metadata

The metadata dictionary (holoscan.core.MetadataDictionary) associated with the operator.

property metadata_policy

The metadata policy (holoscan.core.MetadataPolicy) associated with the operator.

The supported policies are:

• MetadataPolicy.REJECT: Reject the new value if the key already exists

• MetadataPolicy.UPDATE: Replace existing value with the new one if the key already exists

• MetadataPolicy.INPLACE_UPDATE: Update the value stored within an existing MetadataObject in-place if the key already exists (in contrast to UPDATE which always replaces the existing MetadataObject with a new one).

• MetadataPolicy.RAISE: Raise an exception if the key already exists

property name

The name of the operator.

property next_flows

Get the list of flow information for connections to downstream operators.

Returns

list[holoscan.core.FlowInfo]

List of flow information objects describing connections to downstream operators.

property operator_type

The operator type.

holoscan.core.Operator.OperatorType enum representing the type of the operator. The two types currently implemented are native and GXF.

populate_series_attributes(series, sop_instance)

Populates series level attributes in the study data structure.

Parameters:

• study – A DICOM Series instance that needs to be filled-in with series level attribute values

• sop_instance – A sample DICOM SOP Instance that contains the list of attributed which will be parsed

populate_study_attributes(study, sop_instance)

Populates study level attributes in the study data structure.

Parameters:

• study – A DICOM Study instance that needs to be filled-in with study level attribute values

• sop_instance – A sample DICOM SOP Instance that contains the list of attributed which will be parsed

queue_policy(self: holoscan.core._core.OperatorBase, port_name: str, port_type: holoscan.core._core.IOSpec.IOType = <IOType.INPUT: 0>, policy: holoscan.core._core.IOSpec.QueuePolicy = <QueuePolicy.FAULT: 2>) → None

Set the queue policy to be used by an input (or output) port’s receiver (or transmitter).

Parameters

port_namestr

The name of the port.

port_typeIOSpec.IOType, optional

Enum indicating whether port_name corresponds to an input port or output port.

policyIOSpec.QueuePolicy, optional

The queue policy to set. Valid values are:

• QueuePolicy.POP : If the queue is full, pop the oldest item, then add the new one.

• QueuePolicy.REJECT : If the queue is full, reject (discard) the new item.

• QueuePolicy.FAULT : If the queue is full, log a warning and reject the new item.

Returns

transmitterholoscan.resources.Transmitter or None

The transmitter used by this output port. Will be None if the port does not exist.

receiver(self: holoscan.core._core.OperatorBase, port_name: str) → Optional[holoscan::Receiver]

Get the receiver used by an input port.

Parameters

port_namestr

The name of the input port.

Returns

receiverholoscan.resources.Receiver

The receiver used by this input port. Will be None if the port does not exist.

resource(self: holoscan.core._core.OperatorBase, name: str) → object | None

Resources associated with the operator.

Parameters

namestr

The name of the resource to retrieve

Returns

holoscan.core.Resource or None

The resource with the given name. If no resource with the given name is found, None is returned.

property resources

Resources associated with the operator.

service(self: object, service_type: type, id: str = '') → object

Retrieve a registered fragment service through the component’s fragment.

This method delegates to the fragment’s service() method to retrieve a previously registered fragment service by its type and optional identifier. Returns None if no fragment service is found with the specified type and identifier.

Parameters

service_typetype

The type of the fragment service to retrieve. Must be a type that inherits from Resource or FragmentService.

idstr, optional

The identifier of the fragment service. If empty, retrieves by service type only. For Resources, this would typically be the resource’s name.

Returns

object or None

The fragment service instance of the requested type, or None if not found. If the service wraps a Resource and a Resource type is requested, the unwrapped Resource instance is returned.

Raises

RuntimeError

If the component has no associated fragment or if the fragment’s service method cannot be accessed.

Notes

This is a convenience method that internally calls the fragment’s service() method. For services that wrap Resources, the method will automatically unwrap and return the Resource if a Resource type is requested.

setup(spec)

Default implementation of setup method.

property spec

The operator spec (holoscan.core.OperatorSpec) associated with the operator.

start()

Default implementation of start

stop()

Default implementation of stop

stop_execution(self: holoscan.core._core.OperatorBase) → None

Stop the execution of the operator.

This method is used to stop the execution of the operator by setting the internal async condition to EVENT_NEVER state, which sets the scheduling condition to NEVER. Once stopped, the operator will not be scheduled for execution (the compute() method will not be called).

Note that executing this method does not trigger the operator’s stop() method. The stop() method is called only when the scheduler deactivates all operators together.

transmitter(self: holoscan.core._core.OperatorBase, port_name: str) → Optional[holoscan::Transmitter]

Get the transmitter used by an output port.

Parameters

port_namestr

The name of the output port.

Returns

transmitterholoscan.resources.Transmitter or None

The transmitter used by this output port. Will be None if the port does not exist.