docs/changes/newsfragments/450.doc

@@ -0,0 +1 @@
+Add documentation on extending data registries by `Synchon Mandal`_

docs/changes/newsfragments/450.feature

@@ -0,0 +1 @@
+Enable data registries to be extended by exposing :class:`.BasePipelineDataRegistry` and introducing :func:`.register_data_registry` decorator by `Synchon Mandal`_

docs/extending/data_registries.rst

@@ -0,0 +1,70 @@
+.. include:: ../links.inc
+
+.. _data_registries:
+
+Creating a Data Registry
+========================
+
+What is a data registry
+-----------------------
+
+Data Registry is an object which manages pipeline data (like parcellations,
+coordinates and masks) based on the scope. ``junifer`` comes with the
+following in-built data registries:
+
+* :class:`.ParcellationRegistry` for parcellations
+* :class:`.CoordinatesRegistry` for coordinates
+* :class:`.MaskRegistry` for masks
+
+You interact with them indirectly via :func:`.get_data`, :func:`.load_data`,
+:func:`.list_data`, :func:`.register_data` and :func:`.deregister_data`. The
+``kind`` parameter in them directs which data registry to interact with. These
+in turn supply preprocessors and markers with their necessary data for computation.
+
+How to make a data registry
+---------------------------
+
+Ideally you would not need to create a custom data registry if you work with fMRI data.
+In case you work with other modalities like EEG, you might want to create a
+data registry for montages. Here is how you would go about it:
+
+#. Check :ref:`extending junifer <extending_extension>` on how to create a
+   *junifer extension* if you have not done so.
+#. Create the data registry in the *extension script* like so:
+
+   .. code-block:: python
+
+     from junifer.api.decorators import register_data_registry
+     from junifer.data import BasePipelineDataRegistry
+
+
+     @register_data_registry("montage")
+     class MontageDataRegistry(BasePipelineDataRegistry):
+         def __init__(self):
+             super().__init__()
+
+         def register(self):
+             pass
+
+         def deregister(self):
+             pass
+
+         def load(self):
+             pass
+
+         def get(self):
+             pass
+
+
+   * :func:`.register_data_registry` registers a class with the name passed in
+     the argument, ``"montage"`` in this case.
+   * Inheriting from :class:`.BasePipelineDataRegistry` takes care of the class
+     acting as a data registry.
+   * :meth:`.BasePipelineDataRegistry.register`,
+     :meth:`.BasePipelineDataRegistry.deregister`,
+     :meth:`.BasePipelineDataRegistry.load` and
+     :meth:`.BasePipelineDataRegistry.get` need to be implemented
+     (check other registries for reference implementations).
+
+#. Pass ``kind="montage"`` in ``*_data`` functions to
+   verify if your data registry is set up properly.

docs/extending/extension.rst

@@ -5,8 +5,8 @@
 Creating a ``junifer`` extension
 ================================
 
-``junifer`` is designed to be easily extensible. Through the use of a registry
+``junifer`` is designed to be easily extensible. Through the use of data registries,
-and decorators, you can easily add new functionality to ``junifer`` during
+a component registry and decorators, you can easily add new functionality to ``junifer`` during
 runtime. This is done by creating a new Python module and importing it before
 running ``junifer``.
 

docs/extending/index.rst

@@ -31,3 +31,4 @@ DataGrabbers, Preprocessors, Markers, etc.,  following the *junifer* way.
    coordinates
    masks
    plugins
+   data_registries

junifer/api/decorators.py

@@ -5,11 +5,19 @@
 #          Synchon Mandal <s.mandal@fz-juelich.de>
 # License: AGPL
 
+from ..data import DataDispatcher
 from ..pipeline import PipelineComponentRegistry
-from ..typing import DataGrabberLike, MarkerLike, PreprocessorLike, StorageLike
+from ..typing import (
+    DataGrabberLike,
+    DataRegistryLike,
+    MarkerLike,
+    PreprocessorLike,
+    StorageLike,
+)
 
 
 __all__ = [
+    "register_data_registry",
     "register_datagrabber",
     "register_datareader",
     "register_marker",
@@ -30,7 +38,7 @@ def register_datagrabber(klass: DataGrabberLike) -> DataGrabberLike:
 
     Returns
     -------
-    klass: class
+    class
         The unmodified input class.
 
     Notes
@@ -57,7 +65,7 @@ def register_datareader(klass: type) -> type:
 
     Returns
     -------
-    klass: class
+    class
         The unmodified input class.
 
     Notes
@@ -84,7 +92,7 @@ def register_preprocessor(klass: PreprocessorLike) -> PreprocessorLike:
 
     Returns
     -------
-    klass: class
+    class
         The unmodified input class.
 
     """
@@ -107,7 +115,7 @@ def register_marker(klass: MarkerLike) -> MarkerLike:
 
     Returns
     -------
-    klass: class
+    class
         The unmodified input class.
 
     """
@@ -130,7 +138,7 @@ def register_storage(klass: StorageLike) -> StorageLike:
 
     Returns
     -------
-    klass: class
+    class
         The unmodified input class.
 
     """
@@ -139,3 +147,40 @@ def register_storage(klass: StorageLike) -> StorageLike:
         klass=klass,
     )
     return klass
+
+
+def register_data_registry(name: str) -> DataRegistryLike:
+    """Registry registration decorator.
+
+    Registers the data registry as ``name``.
+
+    Parameters
+    ----------
+    name : str
+        The name of the data registry.
+
+    Returns
+    -------
+    class
+        The unmodified input class.
+
+    """
+
+    def decorator(klass: DataRegistryLike) -> DataRegistryLike:
+        """Actual decorator.
+
+        Parameters
+        ----------
+        klass : class
+            The class of the data registry to register.
+
+        Returns
+        -------
+        class
+            The unmodified input class.
+
+        """
+        DataDispatcher()[name] = klass
+        return klass
+
+    return decorator

junifer/api/tests/test_decorators.py

@@ -0,0 +1,32 @@
+"""Provide tests for public decorators."""
+
+# Authors: Synchon Mandal <s.mandal@fz-juelich.de>
+# License: AGPL
+
+from junifer.api.decorators import register_data_registry
+from junifer.data import BasePipelineDataRegistry, DataDispatcher
+
+
+def test_register_data_registry() -> None:
+    """Test data registry registration."""
+
+    @register_data_registry("dumb")
+    class DumDum(BasePipelineDataRegistry):
+        def __init__(self):
+            super().__init__()
+
+        def register(self):
+            pass
+
+        def deregister(self):
+            pass
+
+        def load(self):
+            pass
+
+        def get(self):
+            pass
+
+    assert "dumb" in DataDispatcher()
+    _ = DataDispatcher().pop("dumb")
+    assert "dumb" not in DataDispatcher()

junifer/data/__init__.pyi

@@ -1,5 +1,7 @@
 __all__ = [
+    "BasePipelineDataRegistry",
     "CoordinatesRegistry",
+    "DataDispatcher",
     "ParcellationRegistry",
     "MaskRegistry",
     "get_data",
@@ -12,11 +14,13 @@ __all__ = [
     "utils",
 ]
 
+from .pipeline_data_registry_base import BasePipelineDataRegistry
 from .coordinates import CoordinatesRegistry
 from .parcellations import ParcellationRegistry
 from .masks import MaskRegistry
 
 from ._dispatch import (
+    DataDispatcher,
     get_data,
     list_data,
     load_data,

junifer/data/_dispatch.py

@@ -3,6 +3,7 @@
 # Authors: Synchon Mandal <s.mandal@fz-juelich.de>
 # License: AGPL
 
+from collections.abc import Iterator, MutableMapping
 from pathlib import Path
 from typing import (
     TYPE_CHECKING,
@@ -18,13 +19,14 @@ from ..utils import raise_error
 from .coordinates import CoordinatesRegistry
 from .masks import MaskRegistry
 from .parcellations import ParcellationRegistry
+from .pipeline_data_registry_base import BasePipelineDataRegistry
 
 
 if TYPE_CHECKING:
     from nibabel.nifti1 import Nifti1Image
 
-
 __all__ = [
+    "DataDispatcher",
     "deregister_data",
     "get_data",
     "list_data",
@@ -33,6 +35,77 @@ __all__ = [
 ]
 
 
+class DataDispatcher(MutableMapping):
+    """Class for helping dynamic data dispatch."""
+
+    _instance = None
+
+    def __new__(cls):
+        # Make class singleton
+        if cls._instance is None:
+            cls._instance = super().__new__(cls)
+            # Set registries
+            cls._registries: dict[str, type[BasePipelineDataRegistry]] = {}
+            cls._builtin: dict[str, type[BasePipelineDataRegistry]] = {}
+            cls._external: dict[str, type[BasePipelineDataRegistry]] = {}
+            cls._builtin.update(
+                {
+                    "coordinates": CoordinatesRegistry,
+                    "parcellation": ParcellationRegistry,
+                    "mask": MaskRegistry,
+                }
+            )
+            cls._registries.update(cls._builtin)
+        return cls._instance
+
+    def __getitem__(self, key: str) -> type[BasePipelineDataRegistry]:
+        return self._registries[key]
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self._registries)
+
+    def __len__(self) -> int:
+        return len(self._registries)
+
+    def __delitem__(self, key: str) -> None:
+        # Internal check
+        if key in self._builtin:
+            raise_error(f"Cannot delete in-built key: {key}")
+        # Non-existing key
+        if key not in self._external:
+            raise_error(klass=KeyError, msg=key)
+        # Update external
+        _ = self._external.pop(key)
+        # Update global
+        _ = self._registries.pop(key)
+
+    def __setitem__(
+        self, key: str, value: type[BasePipelineDataRegistry]
+    ) -> None:
+        # Internal check
+        if key in self._builtin:
+            raise_error(f"Cannot set value for in-built key: {key}")
+        # Value type check
+        if not issubclass(value, BasePipelineDataRegistry):
+            raise_error(f"Invalid value type: {type(value)}")
+        # Update external
+        self._external[key] = value
+        # Update global
+        self._registries[key] = value
+
+    def popitem():
+        """Not implemented."""
+        pass
+
+    def clear(self):
+        """Not implemented."""
+        pass
+
+    def setdefault(self, key: str, value=None):
+        """Not implemented."""
+        pass
+
+
 def get_data(
     kind: str,
     names: Union[
@@ -76,27 +149,16 @@ def get_data(
         If ``kind`` is invalid value.
 
     """
-
+    try:
-    if kind == "coordinates":
+        registry = DataDispatcher()[kind]
-        return CoordinatesRegistry().get(
+    except KeyError:
-            coords=names,
-            target_data=target_data,
-            extra_input=extra_input,
-        )
-    elif kind == "parcellation":
-        return ParcellationRegistry().get(
-            parcellations=names,
-            target_data=target_data,
-            extra_input=extra_input,
-        )
-    elif kind == "mask":
-        return MaskRegistry().get(
-            masks=names,
-            target_data=target_data,
-            extra_input=extra_input,
-        )
-    else:  # pragma: no cover
         raise_error(f"Unknown data kind: {kind}")
+    else:
+        return registry().get(
+            names,
+            target_data=target_data,
+            extra_input=extra_input,
+        )
 
 
 def list_data(kind: str) -> list[str]:
@@ -119,14 +181,12 @@ def list_data(kind: str) -> list[str]:
 
     """
 
-    if kind == "coordinates":
+    try:
-        return CoordinatesRegistry().list
+        registry = DataDispatcher()[kind]
-    elif kind == "parcellation":
+    except KeyError:
-        return ParcellationRegistry().list
-    elif kind == "mask":
-        return MaskRegistry().list
-    else:  # pragma: no cover
         raise_error(f"Unknown data kind: {kind}")
+    else:
+        return registry().list
 
 
 def load_data(
@@ -165,15 +225,12 @@ def load_data(
         If ``kind`` is invalid value.
 
     """
-
+    try:
-    if kind == "coordinates":
+        registry = DataDispatcher()[kind]
-        return CoordinatesRegistry().load(name=name)
+    except KeyError:
-    elif kind == "parcellation":
-        return ParcellationRegistry().load(name=name, **kwargs)
-    elif kind == "mask":
-        return MaskRegistry().load(name=name, **kwargs)
-    else:  # pragma: no cover
         raise_error(f"Unknown data kind: {kind}")
+    else:
+        return registry().load(name, **kwargs)
 
 
 def register_data(
@@ -205,20 +262,14 @@ def register_data(
 
     """
 
-    if kind == "coordinates":
+    try:
-        return CoordinatesRegistry().register(
+        registry = DataDispatcher()[kind]
-            name=name, space=space, overwrite=overwrite, **kwargs
+    except KeyError:
-        )
-    elif kind == "parcellation":
-        return ParcellationRegistry().register(
-            name=name, space=space, overwrite=overwrite, **kwargs
-        )
-    elif kind == "mask":
-        return MaskRegistry().register(
-            name=name, space=space, overwrite=overwrite, **kwargs
-        )
-    else:  # pragma: no cover
         raise_error(f"Unknown data kind: {kind}")
+    else:
+        return registry().register(
+            name=name, space=space, overwrite=overwrite, **kwargs
+        )
 
 
 def deregister_data(kind: str, name: str) -> None:
@@ -238,11 +289,9 @@ def deregister_data(kind: str, name: str) -> None:
 
     """
 
-    if kind == "coordinates":
+    try:
-        return CoordinatesRegistry().deregister(name=name)
+        registry = DataDispatcher()[kind]
-    elif kind == "parcellation":
+    except KeyError:
-        return ParcellationRegistry().deregister(name=name)
-    elif kind == "mask":
-        return MaskRegistry().deregister(name=name)
-    else:  # pragma: no cover
         raise_error(f"Unknown data kind: {kind}")
+    else:
+        return registry().deregister(name=name)

junifer/data/coordinates/_coordinates.py

@@ -13,7 +13,6 @@ from junifer_data import get
 from numpy.typing import ArrayLike
 
 from ...utils import logger, raise_error
-from ...utils.singleton import Singleton
 from ..pipeline_data_registry_base import BasePipelineDataRegistry
 from ..utils import JUNIFER_DATA_PARAMS, get_dataset_path, get_native_warper
 from ._ants_coordinates_warper import ANTsCoordinatesWarper
@@ -23,7 +22,7 @@ from ._fsl_coordinates_warper import FSLCoordinatesWarper
 __all__ = ["CoordinatesRegistry"]
 
 
-class CoordinatesRegistry(BasePipelineDataRegistry, metaclass=Singleton):
+class CoordinatesRegistry(BasePipelineDataRegistry):
     """Class for coordinates data registry.
 
     This class is a singleton and is used for managing available coordinates

junifer/data/masks/_masks.py

@@ -24,7 +24,6 @@ from nilearn.masking import (
 )
 
 from ...utils import logger, raise_error
-from ...utils.singleton import Singleton
 from ..pipeline_data_registry_base import BasePipelineDataRegistry
 from ..template_spaces import get_template
 from ..utils import (
@@ -216,7 +215,7 @@ def compute_brain_mask(
     return nimg.new_img_like(target_data["data"], mask)  # type: ignore
 
 
-class MaskRegistry(BasePipelineDataRegistry, metaclass=Singleton):
+class MaskRegistry(BasePipelineDataRegistry):
     """Class for mask data registry.
 
     This class is a singleton and is used for managing available mask

junifer/data/parcellations/_parcellations.py

@@ -16,7 +16,6 @@ import pandas as pd
 from junifer_data import get
 
 from ...utils import logger, raise_error, warn_with_log
-from ...utils.singleton import Singleton
 from ..pipeline_data_registry_base import BasePipelineDataRegistry
 from ..utils import (
     JUNIFER_DATA_PARAMS,
@@ -38,7 +37,7 @@ __all__ = [
 ]
 
 
-class ParcellationRegistry(BasePipelineDataRegistry, metaclass=Singleton):
+class ParcellationRegistry(BasePipelineDataRegistry):
     """Class for parcellation data registry.
 
     This class is a singleton and is used for managing available parcellation

junifer/data/parcellations/tests/test_parcellations.py

@@ -14,6 +14,7 @@ from nilearn.image import new_img_like, resample_to_img
 from numpy.testing import assert_array_almost_equal, assert_array_equal
 
 from junifer.data import (
+    deregister_data,
     get_data,
     list_data,
     load_data,
@@ -1245,3 +1246,9 @@ def test_get_multi_different_space() -> None:
             ],
             target_data=element_data["VBM_GM"],
         )
+
+
+def test_deregister() -> None:
+    """Test parcellation deregistration."""
+    deregister_data(kind="parcellation", name="testparc_3")
+    assert "testparc_3" not in list_data(kind="parcellation")

junifer/data/tests/test_dispatch.py

@@ -0,0 +1,87 @@
+"""Provide tests for data dispatching."""
+
+# Authors: Synchon Mandal <s.mandal@fz-juelich.de>
+# License: AGPL
+
+import pytest
+
+from junifer.data import (
+    BasePipelineDataRegistry,
+    deregister_data,
+    get_data,
+    list_data,
+    load_data,
+    register_data,
+)
+from junifer.data._dispatch import DataDispatcher
+
+
+def test_dispatcher_addition_errors() -> None:
+    """Test registry addition errors."""
+    with pytest.raises(ValueError, match="Cannot set"):
+        DataDispatcher()["mask"] = dict
+
+    with pytest.raises(ValueError, match="Invalid"):
+        DataDispatcher()["masks"] = dict
+
+
+def test_dispatcher_removal_errors() -> None:
+    """Test registry removal errors."""
+    with pytest.raises(ValueError, match="Cannot delete"):
+        _ = DataDispatcher().pop("mask")
+
+    with pytest.raises(KeyError, match="masks"):
+        del DataDispatcher()["masks"]
+
+
+def test_dispatcher() -> None:
+    """Test registry addition and removal."""
+
+    class DumDum(BasePipelineDataRegistry):
+        def register():
+            pass
+
+        def deregister():
+            pass
+
+        def load():
+            pass
+
+        def get():
+            pass
+
+    DataDispatcher().update({"masks": DumDum})
+    assert "masks" in DataDispatcher()
+
+    _ = DataDispatcher().pop("masks")
+    assert "masks" not in DataDispatcher()
+
+
+def test_get_data_error() -> None:
+    """Test error for get_data()."""
+    with pytest.raises(ValueError, match="Unknown data kind"):
+        get_data(kind="planet", names="neptune", target_data={})
+
+
+def test_list_data_error() -> None:
+    """Test error for list_data()."""
+    with pytest.raises(ValueError, match="Unknown data kind"):
+        list_data(kind="planet")
+
+
+def test_load_data_error() -> None:
+    """Test error for load_data()."""
+    with pytest.raises(ValueError, match="Unknown data kind"):
+        load_data(kind="planet", name="neptune")
+
+
+def test_register_data_error() -> None:
+    """Test error for register_data()."""
+    with pytest.raises(ValueError, match="Unknown data kind"):
+        register_data(kind="planet", name="neptune", space="milkyway")
+
+
+def test_deregister_data_error() -> None:
+    """Test error for deregister_data()."""
+    with pytest.raises(ValueError, match="Unknown data kind"):
+        deregister_data(kind="planet", name="neptune")

junifer/typing/__init__.pyi

@@ -1,5 +1,6 @@
 __all__ = [
     "DataGrabberLike",
+    "DataRegistryLike",
     "PreprocessorLike",
     "MarkerLike",
     "StorageLike",
@@ -16,6 +17,7 @@ __all__ = [
 
 from ._typing import (
     DataGrabberLike,
+    DataRegistryLike,
     PreprocessorLike,
     MarkerLike,
     StorageLike,

junifer/typing/_typing.py

@@ -11,6 +11,7 @@ from typing import (
 
 
 if TYPE_CHECKING:
+    from ..data import BasePipelineDataRegistry
     from ..datagrabber import BaseDataGrabber
     from ..datareader import DefaultDataReader
     from ..markers import BaseMarker
@@ -23,6 +24,7 @@ __all__ = [
     "ConfigVal",
     "DataGrabberLike",
     "DataGrabberPatterns",
+    "DataRegistryLike",
     "Dependencies",
     "Element",
     "Elements",
@@ -35,6 +37,7 @@ __all__ = [
 ]
 
 
+DataRegistryLike = type["BasePipelineDataRegistry"]
 DataGrabberLike = type["BaseDataGrabber"]
 PreprocessorLike = type["BasePreprocessor"]
 MarkerLike = type["BaseMarker"]