[WIP] : simplify fpath

mne_bids/path.py

@@ -194,9 +194,10 @@ class BIDSPath(object):
         The "data type" of folder being created at the end of the folder
         hierarchy. E.g., ``'anat'``, ``'func'``, ``'eeg'``, ``'meg'``,
         ``'ieeg'``, etc.
-    root : str | pathlib.Path | None
+    root : str | pathlib.Path
         The root for the filename to be created. E.g., a path to the folder
         in which you wish to create a file with this name.
+        Defaults to ``'.'``.
     check : bool
         If True enforces the entities to be valid according to the
         current BIDS standard. Defaults to True.
@@ -227,7 +228,7 @@ class BIDSPath(object):
     Examples
     --------
     >>> bids_path = BIDSPath(subject='test', session='two', task='mytask',
-                                 suffix='ieeg', extension='.edf')
+                             suffix='ieeg', extension='.edf')
     >>> print(bids_path.basename)
     sub-test_ses-two_task-mytask_ieeg.edf
     >>> bids_path
@@ -261,7 +262,7 @@ class BIDSPath(object):
 
     def __init__(self, subject=None, session=None,
                  task=None, acquisition=None, run=None, processing=None,
-                 recording=None, space=None, split=None, root=None,
+                 recording=None, space=None, split=None, root='.',
                  suffix=None, extension=None, datatype=None, check=True):
         if all(ii is None for ii in [subject, session, task,
                                      acquisition, run, processing,
@@ -409,6 +410,8 @@ def fpath(self):
         # get the inner-most BIDS directory for this file path
         data_path = self.directory
 
+        assert self.root is not None
+
         # account for MEG data that are directory-based
         # else, all other file paths attempt to match
         if self.suffix == 'meg' and self.extension == '.ds':
@@ -420,54 +423,41 @@ def fpath(self):
             # if suffix and/or extension is missing, and root is
             # not None, then BIDSPath will infer the dataset
             # else, return the relative path with the basename
-            if (self.suffix is None or self.extension is None) and \
-                    self.root is not None:
-                # get matching BIDS paths inside the bids root
-                matching_paths = \
-                    _get_matching_bidspaths_from_filesystem(self)
-
-                # FIXME This will break
-                # FIXME e.g. with FIFF data split across multiple files.
-                # if extension is not specified and no unique file path
-                # return filepath of the actual dataset for MEG/EEG/iEEG data
-                if self.suffix is None or self.suffix in ALLOWED_DATATYPES:
-                    # now only use valid datatype extension
-                    valid_exts = sum(ALLOWED_DATATYPE_EXTENSIONS.values(), [])
-                    matching_paths = [p for p in matching_paths
-                                      if _parse_ext(p)[1] in valid_exts]
-
-                if (self.split is None and
-                        (not matching_paths or
-                         '_split-' in matching_paths[0])):
-                    # try finding FIF split files (only first one)
-                    this_self = self.copy().update(split='01')
-                    matching_paths = \
-                        _get_matching_bidspaths_from_filesystem(this_self)
-
-                # found no matching paths
-                if not matching_paths:
-                    msg = (f'Could not locate a data file of a supported '
-                           f'format. This is likely a problem with your '
-                           f'BIDS dataset. Please run the BIDS validator '
-                           f'on your data. (root={self.root}, '
-                           f'basename={self.basename}). '
-                           f'{matching_paths}')
-                    warn(msg)
 
-                    bids_fpath = op.join(data_path, self.basename)
-                # if paths still cannot be resolved, then there is an error
-                elif len(matching_paths) > 1:
-                    msg = ('Found more than one matching data file for the '
-                           'requested recording. Cannot proceed due to the '
-                           'ambiguity. This is likely a problem with your '
-                           'BIDS dataset. Please run the BIDS validator on '
-                           'your data.')
-                    raise RuntimeError(msg)
-                else:
-                    bids_fpath = matching_paths[0]
+            # get matching BIDS paths inside the bids root
+            matching_paths = \
+                _get_matching_bidspaths_from_filesystem(self)
+
+            # FIXME This will break
+            # FIXME e.g. with FIFF data split across multiple files.
+            # if extension is not specified and no unique file path
+            # return filepath of the actual dataset for MEG/EEG/iEEG data
+            if self.suffix is None or self.suffix in ALLOWED_DATATYPES:
+                # now only use valid datatype extension
+                valid_exts = sum(ALLOWED_DATATYPE_EXTENSIONS.values(), [])
+                matching_paths = [p for p in matching_paths
+                                  if _parse_ext(p)[1] in valid_exts]
+
+            if (self.split is None and self.suffix is None and
+                    self.extension is None and
+                    (not matching_paths or
+                     '_split-' in matching_paths[0])):
+                # try finding FIF split files (only first one)
+                this_self = self.copy().update(split='01')
+                matching_paths = \
+                    _get_matching_bidspaths_from_filesystem(this_self)
 
-            else:
+            if not matching_paths:  # found no matching paths
                 bids_fpath = op.join(data_path, self.basename)
+            elif len(matching_paths) > 1:
+                msg = ('Found more than one matching data file for the '
+                       'requested recording. Cannot proceed due to the '
+                       'ambiguity. This is likely a problem with your '
+                       'BIDS dataset. Please run the BIDS validator on '
+                       'your data.')
+                raise RuntimeError(msg)
+            else:
+                bids_fpath = matching_paths[0]
 
         bids_fpath = Path(bids_fpath)
         return bids_fpath

mne_bids/tests/test_path.py

@@ -365,15 +365,15 @@ def test_bids_path_inference(return_bids_test_dir):
     with pytest.raises(RuntimeError, match='Found more than one'):
         bids_path.fpath
 
-    # can't locate a file, but the basename should work
-    bids_path = BIDSPath(
-        subject=subject_id, session=session_id, acquisition=acq,
-        task=task, run='10', root=bids_root)
-    with pytest.warns(RuntimeWarning, match='Could not locate'):
-        fpath = bids_path.fpath
-        assert str(fpath) == op.join(bids_root, f'sub-{subject_id}',
-                                     f'ses-{session_id}',
-                                     bids_path.basename)
+    # # can't locate a file, but the basename should work
+    # bids_path = BIDSPath(
+    #     subject=subject_id, session=session_id, acquisition=acq,
+    #     task=task, run='10', root=bids_root)
+    # with pytest.warns(RuntimeWarning, match='Could not locate'):
+    #     fpath = bids_path.fpath
+    #     assert str(fpath) == op.join(bids_root, f'sub-{subject_id}',
+    #                                  f'ses-{session_id}',
+    #                                  bids_path.basename)
 
     # shouldn't error out when there is no uncertainty
     channels_fname = BIDSPath(subject=subject_id, session=session_id,
@@ -404,9 +404,11 @@ def test_bids_path(return_bids_test_dir):
     """Test usage of BIDSPath object."""
     bids_root = return_bids_test_dir
 
-    bids_path = BIDSPath(
+    bids_path_kwargs = dict(
         subject=subject_id, session=session_id, run=run, acquisition=acq,
-        task=task, root=bids_root, suffix='meg')
+        task=task, suffix='meg'
+    )
+    bids_path = BIDSPath(root=bids_root, **bids_path_kwargs)
 
     expected_parent_dir = op.join(bids_root, f'sub-{subject_id}',
                                   f'ses-{session_id}', 'meg')
@@ -420,7 +422,7 @@ def test_bids_path(return_bids_test_dir):
     assert op.dirname(bids_path.fpath).startswith(bids_root)
 
     # when bids root is not passed in, passes relative path
-    bids_path2 = bids_path.copy().update(datatype='meg', root=None)
+    bids_path2 = BIDSPath(datatype='meg', **bids_path_kwargs)
     expected_relpath = op.join(
         f'sub-{subject_id}', f'ses-{session_id}', 'meg',
         expected_basename + '_meg')