[ENH] Add tasks for reading BIDS files and dataset

clinica/pydra/tasks/__init__.py

@@ -1,4 +1,5 @@
 from .parsers import parse_bids_file
+from .readers import read_bids, read_bids_dataset, read_bids_files
 from .templates import (
     download_mni_template_2009a,
     download_mni_template_2009c,

clinica/pydra/tasks/readers.py

@@ -0,0 +1,123 @@
+from __future__ import annotations
+
+from os import PathLike
+from pathlib import Path
+from typing import Optional, Sequence
+
+from pydra.engine import Workflow
+from pydra.mark import annotate, task
+
+__all__ = ["read_bids", "read_bids_dataset", "read_bids_files"]
+
+
+@task
+@annotate(
+    {
+        "return": {
+            "dataset_description": Optional[dict],
+            "participant_ids": list[str],
+            "session_ids": Optional[list[str]],
+        }
+    }
+)
+def read_bids_dataset(dataset_path: PathLike):
+    dataset_path = Path(dataset_path).resolve()
+    description_file = dataset_path / "dataset_description.json"
+    dataset_description = (
+        json.load(description_file.read_text()) if description_file.exists() else None
+    )
+
+    try:
+        _ = next(dataset_path.glob("*/ses-*"))
+        multi_sessions = True
+    except StopIteration:
+        multi_sessions = False
+
+    if multi_sessions:
+        visits = dataset_path.glob("sub-*/ses-*")
+        participant_ids, session_ids = list(
+            map(
+                list,
+                zip(
+                    *(
+                        str(visit.relative_to(dataset_path)).split("/")
+                        for visit in visits
+                    )
+                ),
+            )
+        )
+    else:
+        visits = dataset_path.glob("sub-*")
+        participant_ids = sorted(
+            str(visit.relative_to(dataset_path)) for visit in visits
+        )
+        session_ids = None
+
+    return dataset_description, participant_ids, session_ids
+
+
+@task
+@annotate({"return": {"files": list[Path]}})
+def read_bids_files(
+    dataset_path: PathLike,
+    participant_ids: Sequence[str] | None = None,
+    session_ids: Sequence[str] | None = None,
+    datatype: str | None = None,
+    suffix: str | None = None,
+    extension: str | None = None,
+):
+    dataset_path = Path(dataset_path).resolve()
+    datatype = datatype or "*"
+    suffix = suffix or "*"
+    extension = extension or "*"
+    files = []
+
+    if all([participant_ids, session_ids]):
+        for participant_id, session_id in zip([participant_ids, session_ids]):
+            dir_pattern = f"{participant_id}/{session_id}/{datatype}"
+            name_pattern = f"{participant_id}_{session_id}*_{suffix}.{extension}"
+            file_pattern = f"{dir_pattern}/{name_pattern}"
+            files += sorted(dataset_path.glob(file_pattern))
+    elif participant_ids:
+        for participant_id in participant_ids:
+            dir_pattern = f"{participant_id}/**/{datatype}"
+            name_pattern = f"{participant_id}*_{suffix}.{extension}"
+            file_pattern = f"{dir_pattern}/{name_pattern}"
+            files += sorted(dataset_path.glob(file_pattern))
+    else:
+        dir_pattern = f"**/{datatype}"
+        name_pattern = f"*_{suffix}.{extension}"
+        file_pattern = f"{dir_pattern}/{name_pattern}"
+        files += sorted(dataset_path.glob(file_pattern))
+
+    return files
+
+
+def read_bids(output_queries: dict, **kwargs) -> Workflow:
+    workflow = Workflow(name="read_bids", input_spec=["dataset_path"], **kwargs)
+
+    workflow.add(
+        read_bids_dataset(
+            name="read_bids_dataset", dataset_path=workflow.lzin.dataset_path
+        )
+    )
+    connections = {
+        "dataset_description": workflow.read_bids_dataset.lzout.dataset_description,
+        "participant_ids": workflow.read_bids_dataset.lzout.participant_ids,
+        "session_ids": workflow.read_bids_dataset.lzout.session_ids,
+    }
+
+    for output_name, bids_query in output_queries.items():
+        task_ = read_bids_files(
+            name=f"read_{output_name}",
+            dataset_path=workflow.lzin.dataset_path,
+            participant_ids=workflow.read_bids_dataset.lzout.participant_ids,
+            session_ids=workflow.read_bids_dataset.lzout.session_ids,
+            **bids_query,
+        )
+        workflow.add(task_)
+        connections.update({output_name: task_.lzout.files})
+
+    workflow.set_output(connections=connections)
+
+    return workflow

clinica/pydra/tasks/templates.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from pathlib import PurePath
 
 from pydra.mark import annotate, task