API Reference

This section provides detailed API documentation for the ndx-hed extension.

Core Classes

HedLabMetaData

class HedLabMetaData(*args: Any, **kwargs: Any)[source]

Bases:

__init__(hed_schema_version, definitions=None)[source]
Parameters:
  • hed_schema_version (str) – The version of HED used by this data.

  • definitions (str) – A string containing one or more HED definitions.

HedTags

class HedTags(*args, **kwargs)[source]

Bases: VectorData

Column storing HED (Hierarchical Event Descriptors) annotations for a row. A HED string is a comma-separated, and possibly parenthesized list of HED tags selected from a valid HED vocabulary as specified by the NWBFile field HedVersion.

__init__(name='HED', description='Column that stores HED tags as text annotating their respective row.', data=[])[source]
Parameters:
  • name (str) – The name of this VectorData

  • description (str) – a description for this column

  • data (ndarray or list or tuple or Dataset or StrDataset or HDMFDataset or AbstractDataChunkIterator or DataIO) – a dataset where the first dimension is a concatenation of multiple vectors

add_row(val)[source]

Append a data value to this column.

Parameters:

val (str) – the value to add to this column. Should be a valid HED string – just forces string.

all_children()

Get a list of all child objects and their child objects recursively.

If the object has an object_id, the object will be added to “ret” to be returned. If that object has children, they will be added to the “stack” in order to be: 1) Checked to see if has an object_id, if so then add to “ret” 2) Have children that will also be checked

property all_objects

Get a LabelledDict that indexed all child objects and their children by object ID.

append(arg)
property children
property container_source

The source of this Container

property data
data_type = 'VectorData'
property description

a description for this column

extend(ar, **kwargs)

Add all elements of the iterable arg to the end of this VectorData.

Each subclass of VectorData should have its own extend method to ensure functionality and efficiency.

Parameters:

arg – The iterable to add to the end of this VectorData

property fields

Subclasses use this class attribute to add properties to autogenerate. fields allows for lists and for dicts with the keys {‘name’, ‘child’, ‘required_name’, ‘doc’, ‘settable’}. 1. name: The name of the field property 2. child: A boolean value to set the parent/child relationship between the field property and the container. 3. required_name: The name the field property must have such that name matches required_name. 4. doc: Documentation of the field property 5. settable: If true, a setter function is created so that the field can be changed after creation.

generate_new_id(recurse=True)

Changes the object ID of this Container and all of its children to a new UUID string.

Parameters:

recurse (bool) – whether or not to change the object ID of this container’s children

get(key, **kwargs)

Retrieve elements from this VectorData

Parameters:
  • key – Selection of the elements

  • kwargs – Ignored

get_ancestor(data_type=None)

Traverse parent hierarchy and return first instance of the specified data_type

Parameters:

data_type (str) – the data_type to search for

get_ancestors()
classmethod get_fields_conf()
get_read_io()

Get the io object used to read this container.

If self.read_io is None, this function will iterate through the parents and return the first io object found on a parent container

Returns:

The HDMFIO object used to read this container. Returns None in case no io object is found, e.g., in case this container has not been read from file.

property modified
property name

The name of this Container

namespace = 'ndx-hed'
neurodata_type = 'HedTags'
property object_id
property parent

The parent Container of this Container

property read_io

The HDMFIO object used for reading the container.

This property will typically be None if this Container is not a root Container (i.e., if parent is not None). Use get_read_io instead if you want to retrieve the HDMFIO object used for reading from the parent container.

reset_parent()

Reset the parent of this Container to None and remove the Container from the children of its parent.

Use with caution. This can result in orphaned containers and broken links.

set_data_io(data_io_class: Type[DataIO], data_io_kwargs: dict, data_chunk_iterator_class: Type[AbstractDataChunkIterator] | None = None, data_chunk_iterator_kwargs: dict = None) None

Apply DataIO object to the data held by this Data object.

Parameters:
  • data_io_class (Type[DataIO]) – The DataIO to apply to the data held by this Data.

  • data_io_kwargs (dict) – The keyword arguments to pass to the DataIO.

  • data_chunk_iterator_class (Type[AbstractDataChunkIterator]) – The DataChunkIterator to use for the DataIO. If None, no DataChunkIterator is used.

  • data_chunk_iterator_kwargs (dict) – The keyword arguments to pass to the DataChunkIterator.

Notes

If data_chunk_iterator_class is not None, the data is wrapped in the DataChunkIterator before being wrapped in the DataIO. This allows for rewriting the backend configuration of hdf5 datasets.

set_modified(modified=True)
Parameters:

modified (bool) – whether or not this Container has been modified

property shape

Get the shape of the data represented by this container :return: Shape tuple :rtype: tuple of ints

transform(func)

Transform data from the current underlying state.

This function can be used to permanently load data from disk, or convert to a different representation, such as a torch.Tensor

Parameters:

func (function) – a function to transform data

classmethod type_hierarchy()

HedValueVector

class HedValueVector(*args, **kwargs)[source]

Bases: VectorData

Column storing values and a single HED annotation that applies to all values in the column. A HED string is a comma-separated, and possibly parenthesized list of HED tags selected from a valid HED vocabulary as specified by the NWBFile field HedVersion.

__init__(name, description, hed, data=[])[source]
Parameters:
  • name (str) – the name of this VectorData

  • description (str) – a description for this column

  • hed (str) – HED annotation template for all values in the column

  • data (ndarray or list or tuple or Dataset or StrDataset or HDMFDataset or AbstractDataChunkIterator or DataIO) – a dataset where the first dimension is a concatenation of multiple vectors

add_row(val)

Append a data value to this VectorData column

Parameters:

val (None) – the value to add to this column

all_children()

Get a list of all child objects and their child objects recursively.

If the object has an object_id, the object will be added to “ret” to be returned. If that object has children, they will be added to the “stack” in order to be: 1) Checked to see if has an object_id, if so then add to “ret” 2) Have children that will also be checked

property all_objects

Get a LabelledDict that indexed all child objects and their children by object ID.

append(arg)
property children
property container_source

The source of this Container

property data
data_type = 'VectorData'
property description

a description for this column

extend(ar, **kwargs)

Add all elements of the iterable arg to the end of this VectorData.

Each subclass of VectorData should have its own extend method to ensure functionality and efficiency.

Parameters:

arg – The iterable to add to the end of this VectorData

property fields

Subclasses use this class attribute to add properties to autogenerate. fields allows for lists and for dicts with the keys {‘name’, ‘child’, ‘required_name’, ‘doc’, ‘settable’}. 1. name: The name of the field property 2. child: A boolean value to set the parent/child relationship between the field property and the container. 3. required_name: The name the field property must have such that name matches required_name. 4. doc: Documentation of the field property 5. settable: If true, a setter function is created so that the field can be changed after creation.

generate_new_id(recurse=True)

Changes the object ID of this Container and all of its children to a new UUID string.

Parameters:

recurse (bool) – whether or not to change the object ID of this container’s children

get(key, **kwargs)

Retrieve elements from this VectorData

Parameters:
  • key – Selection of the elements

  • kwargs – Ignored

get_ancestor(data_type=None)

Traverse parent hierarchy and return first instance of the specified data_type

Parameters:

data_type (str) – the data_type to search for

get_ancestors()
classmethod get_fields_conf()
get_read_io()

Get the io object used to read this container.

If self.read_io is None, this function will iterate through the parents and return the first io object found on a parent container

Returns:

The HDMFIO object used to read this container. Returns None in case no io object is found, e.g., in case this container has not been read from file.

property hed

Return the HED annotation template for this column.

property modified
property name

The name of this Container

namespace = 'ndx-hed'
neurodata_type = 'HedValueVector'
property object_id
property parent

The parent Container of this Container

property read_io

The HDMFIO object used for reading the container.

This property will typically be None if this Container is not a root Container (i.e., if parent is not None). Use get_read_io instead if you want to retrieve the HDMFIO object used for reading from the parent container.

reset_parent()

Reset the parent of this Container to None and remove the Container from the children of its parent.

Use with caution. This can result in orphaned containers and broken links.

set_data_io(data_io_class: Type[DataIO], data_io_kwargs: dict, data_chunk_iterator_class: Type[AbstractDataChunkIterator] | None = None, data_chunk_iterator_kwargs: dict = None) None

Apply DataIO object to the data held by this Data object.

Parameters:
  • data_io_class (Type[DataIO]) – The DataIO to apply to the data held by this Data.

  • data_io_kwargs (dict) – The keyword arguments to pass to the DataIO.

  • data_chunk_iterator_class (Type[AbstractDataChunkIterator]) – The DataChunkIterator to use for the DataIO. If None, no DataChunkIterator is used.

  • data_chunk_iterator_kwargs (dict) – The keyword arguments to pass to the DataChunkIterator.

Notes

If data_chunk_iterator_class is not None, the data is wrapped in the DataChunkIterator before being wrapped in the DataIO. This allows for rewriting the backend configuration of hdf5 datasets.

set_modified(modified=True)
Parameters:

modified (bool) – whether or not this Container has been modified

property shape

Get the shape of the data represented by this container :return: Shape tuple :rtype: tuple of ints

transform(func)

Transform data from the current underlying state.

This function can be used to permanently load data from disk, or convert to a different representation, such as a torch.Tensor

Parameters:

func (function) – a function to transform data

classmethod type_hierarchy()

Validation Utilities

HedNWBValidator

class HedNWBValidator(*args: Any, **kwargs: Any)[source]

Bases:

__init__(hed_metadata: HedLabMetaData)[source]

Initialize the HedNWBValidator with HED metadata.

Parameters:

hed_metadata (HedLabMetaData) – The HED lab metadata containing schema information. Must be a valid HedLabMetaData instance with a loaded HED schema. If the HedLabMetaData was constructed successfully, it is guaranteed to have a valid schema.

Raises:

ValueError – If hed_metadata is not an instance of HedLabMetaData

Notes

HedLabMetaData validates the schema during its own construction, so if a HedLabMetaData instance exists, it is guaranteed to have a valid HED schema and version. No additional validation is needed here.

BIDS Conversion Utilities

These utilities support bidirectional conversion between BIDS events and NWB EventsTable format.

extract_definitions(sidecar_data: dict, hed_schema: HedSchema | HedSchemaGroup) tuple[source]

Extracts definitions from a HED sidecar JSON data using the provided HED schema.

Parameters:
  • sidecar_data (dict) – A dictionary representing the loaded HED Sidecar JSON data.

  • hed_schema (HedSchema or HedSchemaGroup) – The HED schema object for validation and processing.

Returns:

A tuple containing:
  • DefinitionDict: A dictionary of definitions extracted from the sidecar.

  • list: A list of validation issues found during extraction.

Return type:

tuple

extract_meanings(sidecar_data: dict) dict[source]

Converts a HED sidecar JSON data to a meanings dictionary.

Parameters:

sidecar_data (dict) – A dictionary representing the loaded HED Sidecar JSON data.

Returns:

A meanings dictionary with keys “categorical” and “value”
  • ”categorical”: dict mapping column names to a dict of {category: (description, HED string)}

  • ”value”: dict mapping column names to HED strings

Return type:

dict

get_bids_events(events_table: EventsTable) tuple[source]

Converts an EventsTable back to BIDS format (DataFrame and JSON sidecar).

Parameters:

events_table (EventsTable) – The EventsTable to convert.

Returns:

A tuple containing:
  • pd.DataFrame: The events data with proper column names (onset, duration, etc.)

  • dict: The JSON sidecar data with column metadata, levels, and HED annotations

Return type:

tuple

get_categorical_meanings(column_name: str, column_info: dict) MeaningsTable[source]

Converts a categorical column info dict to a MeaningsTable.

Parameters:
  • column_name (str) – The name of the column.

  • column_info (dict) – The column info dictionary from the sidecar.

Returns:

The constructed MeaningsTable object.

Return type:

MeaningsTable

get_events_table(name: str, description: str, df: DataFrame, meanings: dict) EventsTable[source]

Converts a pandas DataFrame and meanings dictionary to an EventsTable.

Parameters:
  • name (str) – The name of the EventsTable.

  • description (str) – The description of the EventsTable.

  • df (pd.DataFrame) – The DataFrame containing event data.

  • meanings (dict) – The meanings dictionary with keys “categorical” and “value”.

Returns:

The constructed EventsTable object.

Return type:

EventsTable