docs/changes/newsfragments/298.feature

@@ -0,0 +1 @@
+Introduce :func:`.get_template` to fetch template space image tailored to a target data by `Synchon Mandal`_

junifer/api/tests/test_api_utils.py

@@ -44,6 +44,7 @@ def test_get_dependency_information_short() -> None:
         "ruamel.yaml",
         "httpx",
         "tqdm",
+        "templateflow",
     ]
     if int(pl.python_version_tuple()[1]) < 10:
         dependency_list.append("importlib_metadata")
@@ -68,6 +69,7 @@ def test_get_dependency_information_long() -> None:
         "ruamel.yaml",
         "httpx",
         "tqdm",
+        "templateflow",
     ]
     for key in dependency_list:
         assert key in dependency_information_keys

junifer/data/__init__.py

@@ -25,6 +25,6 @@ from .masks import (
     get_mask,
 )
 
-from .template_spaces import get_xfm
+from .template_spaces import get_template, get_xfm
 
 from . import utils

junifer/data/template_spaces.py

@@ -4,11 +4,15 @@
 # License: AGPL
 
 from pathlib import Path
-from typing import Union
+from typing import Any, Dict, Optional, Union
 
 import httpx
+import nibabel as nib
+import numpy as np
+from templateflow import api as tflow
 
 from ..utils import logger, raise_error
+from .utils import closest_resolution
 
 
 def get_xfm(
@@ -89,3 +93,71 @@ def get_xfm(
                     f.write(chunk)
 
     return xfm_file_path
+
+
+def get_template(
+    space: str,
+    target_data: Dict[str, Any],
+    extra_input: Optional[Dict[str, Any]] = None,
+) -> nib.Nifti1Image:
+    """Get template for the space, tailored for the target image.
+
+    Parameters
+    ----------
+    space : str
+        The name of the template space.
+    target_data : dict
+        The corresponding item of the data object for which the template space
+        will be loaded.
+    extra_input : dict, optional
+        The other fields in the data object. Useful for accessing other data
+        types (default None).
+
+    Returns
+    -------
+    Nifti1Image
+        The template image.
+
+    Raises
+    ------
+    ValueError
+        If ``space`` is invalid.
+    RuntimeError
+        If template in the required resolution is not found.
+
+    """
+    # Check for invalid space; early check to raise proper error
+    if space not in tflow.templates():
+        raise_error(f"Unknown template space: {space}")
+
+    # Get the min of the voxels sizes and use it as the resolution
+    target_img = target_data["data"]
+    resolution = np.min(target_img.header.get_zooms()[:3]).astype(int)
+
+    # Fetch available resolutions for the template
+    available_resolutions = [
+        int(min(val["zooms"]))
+        for val in tflow.get_metadata(space)["res"].values()
+    ]
+    # Use the closest resolution if desired resolution is not found
+    resolution = closest_resolution(resolution, available_resolutions)
+
+    logger.info(f"Downloading template {space} in resolution {resolution}")
+    # Retrieve template
+    try:
+        template_path = tflow.get(
+            space,
+            raise_empty=True,
+            resolution=resolution,
+            suffix="T1w",
+            desc=None,
+            extension="nii.gz",
+        )
+    except Exception:  # noqa: BLE001
+        raise_error(
+            f"Template {space} not found in the required resolution "
+            f"{resolution}",
+            klass=RuntimeError,
+        )
+    else:
+        return nib.load(template_path)  # type: ignore

junifer/data/tests/test_template_spaces.py

@@ -6,9 +6,12 @@
 import socket
 from pathlib import Path
 
+import nibabel as nib
 import pytest
 
-from junifer.data import get_xfm
+from junifer.data import get_template, get_xfm
+from junifer.datareader import DefaultDataReader
+from junifer.testing.datagrabbers import OasisVBMTestingDataGrabber
 
 
 @pytest.mark.skipif(
@@ -28,3 +31,39 @@ def test_get_xfm(tmp_path: Path) -> None:
         src="MNI152NLin6Asym", dst="MNI152NLin2009cAsym", xfms_dir=tmp_path
     )
     assert isinstance(xfm_path, Path)
+
+
+def test_get_template() -> None:
+    """Test tailored template image fetch."""
+    with OasisVBMTestingDataGrabber() as dg:
+        element = dg["sub-01"]
+        element_data = DefaultDataReader().fit_transform(element)
+        vbm_gm = element_data["VBM_GM"]
+        # Get tailored parcellation
+        tailored_template = get_template(
+            space=vbm_gm["space"], target_data=vbm_gm
+        )
+        assert isinstance(tailored_template, nib.Nifti1Image)
+
+
+def test_get_template_invalid_space() -> None:
+    """Test invalid space check for template fetch."""
+    with OasisVBMTestingDataGrabber() as dg:
+        element = dg["sub-01"]
+        element_data = DefaultDataReader().fit_transform(element)
+        vbm_gm = element_data["VBM_GM"]
+        # Get tailored parcellation
+        with pytest.raises(ValueError, match="Unknown template space:"):
+            _ = get_template(space="andromeda", target_data=vbm_gm)
+
+
+def test_get_template_closest_resolution() -> None:
+    """Test closest resolution check for template fetch."""
+    with OasisVBMTestingDataGrabber() as dg:
+        element = dg["sub-01"]
+        element_data = DefaultDataReader().fit_transform(element)
+        vbm_gm = element_data["VBM_GM"]
+        # Change header resolution to fetch closest resolution
+        element_data["VBM_GM"]["data"].header.set_zooms((3, 3, 3))
+        template = get_template(space=vbm_gm["space"], target_data=vbm_gm)
+        assert isinstance(template, nib.Nifti1Image)

junifer/data/utils.py

@@ -8,14 +8,14 @@ from ..utils.logging import logger
 
 
 def closest_resolution(
-    resolution: Optional[float],
+    resolution: Optional[Union[float, int]],
     valid_resolution: Union[List[float], List[int], np.ndarray],
 ) -> Union[float, int]:
     """Find the closest resolution.
 
     Parameters
     ----------
-    resolution : float, optional
+    resolution : float or int, optional
         The given resolution. If None, will return the highest resolution
         (default None).
     valid_resolution : list of float or int, or np.ndarray

pyproject.toml

@@ -48,6 +48,7 @@ dependencies = [
     "h5py>=3.8.0,<3.10",
     "httpx[http2]==0.26.0",
     "tqdm==4.66.1",
+    "templateflow>=23.0.0",
 ]
 dynamic = ["version"]
 
@@ -188,8 +189,10 @@ known-third-party =[
     "nilearn",
     "sqlalchemy",
     "yaml",
+    "importlib_metadata",
     "httpx",
     "tqdm",
+    "templateflow",
     "bct",
     "neurokit2",
     "pytest",