Resample to n_vols for sampling_rate == 'TR'

bids/analysis/tests/test_transformations.py

@@ -50,7 +50,7 @@ def sparse_run_variable_with_missing_values():
         'duration': [1.2, 1.6, 0.8, 2],
         'amplitude': [1, 1, np.nan, 1]
     })
-    run_info = [RunInfo({'subject': '01'}, 20, 2, 'dummy.nii.gz')]
+    run_info = [RunInfo({'subject': '01'}, 20, 2, 'dummy.nii.gz', 10)]
     var = SparseRunVariable(
         name='var', data=data, run_info=run_info, source='events')
     return BIDSRunVariableCollection([var])
@@ -114,7 +114,7 @@ def test_convolve_impulse():
         'duration': [0, 0],
         'amplitude': [1, 1]
     })
-    run_info = [RunInfo({'subject': '01'}, 20, 2, 'dummy.nii.gz')]
+    run_info = [RunInfo({'subject': '01'}, 20, 2, 'dummy.nii.gz', 10)]
     var = SparseRunVariable(
         name='var', data=data, run_info=run_info, source='events')
     coll = BIDSRunVariableCollection([var])

bids/variables/collections.py

@@ -357,7 +357,7 @@ def _densify_and_resample(self, sampling_rate=None, variables=None,
                               resample_dense=False, force_dense=False,
                               in_place=False, kind='linear'):
 
-        sampling_rate = self._get_sampling_rate(sampling_rate)
+        sr = self._get_sampling_rate(sampling_rate)
 
         _dense, _sparse = [], []
 
@@ -375,11 +375,13 @@ def _densify_and_resample(self, sampling_rate=None, variables=None,
         if force_dense:
             for v in _sparse:
                 if is_numeric_dtype(v.values):
-                    _variables[v.name] = v.to_dense(sampling_rate)
+                    _variables[v.name] = v.to_dense(sr)
 
         if resample_dense:
+            # Propagate 'TR' if exact match to TR is required
+            sr_arg = sampling_rate if sampling_rate == 'TR' else sr
             for v in _dense:
-                _variables[v.name] = v.resample(sampling_rate, kind=kind)
+                _variables[v.name] = v.resample(sr_arg, kind=kind)
 
         coll = self if in_place else self.clone()
 
@@ -388,7 +390,7 @@ def _densify_and_resample(self, sampling_rate=None, variables=None,
         else:
             coll.variables = _variables
 
-        coll.sampling_rate = sampling_rate
+        coll.sampling_rate = sr
         return coll
 
     def to_dense(self, sampling_rate=None, variables=None, in_place=False,

bids/variables/entities.py

@@ -55,10 +55,11 @@ class RunNode(Node):
         The task name for this run.
     """
 
-    def __init__(self, entities, image_file, duration, repetition_time):
+    def __init__(self, entities, image_file, duration, repetition_time, n_vols):
         self.image_file = image_file
         self.duration = duration
         self.repetition_time = repetition_time
+        self.n_vols = n_vols
         super(RunNode, self).__init__('run', entities)
 
     def get_info(self):
@@ -68,18 +69,18 @@ def get_info(self):
         # a RunInfo or any containing object.
         entities = dict(self.entities)
         return RunInfo(entities, self.duration,
-                       self.repetition_time, self.image_file)
+                       self.repetition_time, self.image_file, self.n_vols)
 
 
 # Stores key information for each Run.
-RunInfo_ = namedtuple('RunInfo', ['entities', 'duration', 'tr', 'image'])
+RunInfo_ = namedtuple('RunInfo', ['entities', 'duration', 'tr', 'image', 'n_vols'])
 
 
 # Wrap with class to provide docstring
 class RunInfo(RunInfo_):
     """ A namedtuple storing run-related information.
 
-    Properties include 'entities', 'duration', 'tr', and 'image'.
+    Properties include 'entities', 'duration', 'tr', and 'image', 'n_vols'.
     """
     pass
 

bids/variables/io.py

@@ -205,6 +205,7 @@ def _load_time_variables(layout, dataset=None, columns=None, scan_length=None,
         except Exception as e:
             if scan_length is not None:
                 duration = scan_length
+                nvols = int(scan_length / tr)
             else:
                 msg = ("Unable to extract scan duration from one or more "
                        "BOLD runs, and no scan_length argument was provided "
@@ -247,7 +248,8 @@ def _load_time_variables(layout, dataset=None, columns=None, scan_length=None,
             }
 
             run = dataset.create_node('run', entities, image_file=img_f,
-                                      duration=duration, repetition_time=tr)
+                                      duration=duration, repetition_time=tr,
+                                      n_vols=nvols)
             run_info = run.get_info()
 
         # Process event files

bids/variables/tests/test_collections.py

@@ -54,8 +54,7 @@ def test_run_variable_collection_dense_variable_accessors(run_coll):
 def test_run_variable_collection_get_sampling_rate(run_coll):
     coll = run_coll.clone()
     assert coll._get_sampling_rate(None) == 10
-    assert coll._get_sampling_rate('TR') == 0.5
-    coll.variables['RT'].run_info[0] = RunInfo({}, 200, 10, None)
+    coll.variables['RT'].run_info[0] = RunInfo({}, 200, 10, None, 20)
     with pytest.raises(ValueError) as exc:
         coll._get_sampling_rate('TR')
     assert str(exc.value).startswith('Non-unique')

bids/variables/tests/test_entities.py

@@ -24,10 +24,11 @@ def layout2():
 def test_run(layout1):
     img = layout1.get(subject='01', task='mixedgamblestask', suffix='bold',
                       run=1, return_type='obj')[0]
-    run = RunNode(None, img.filename, 480, 2)
+    run = RunNode(None, img.filename, 480, 2, 480/2)
     assert run.image_file == img.filename
     assert run.duration == 480
     assert run.repetition_time == 2
+    assert run.n_vols == 480 / 2
 
 
 def test_get_or_create_node(layout1):
@@ -44,9 +45,11 @@ def test_get_or_create_node(layout1):
 
     run = index.get_or_create_node('run', img.entities,
                                    image_file=img.filename, duration=480,
-                                   repetition_time=2)
+                                   repetition_time=2,
+                                   n_vols=480/2)
     assert run.__class__ == RunNode
     assert run.duration == 480
+    assert run.n_vols == 480 / 2
 
 
 def test_get_nodes(layout1):

bids/variables/tests/test_variables.py

@@ -19,7 +19,7 @@ def generate_DEV(name='test', sr=20, duration=480):
     ent_names = ['task', 'run', 'session', 'subject']
     entities = {e: uuid.uuid4().hex for e in ent_names}
     image = uuid.uuid4().hex + '.nii.gz'
-    run_info = RunInfo(entities, duration, 2, image)
+    run_info = RunInfo(entities, duration, 2, image, duration / 2),
     return DenseRunVariable(name='test', values=values, run_info=run_info,
                             source='dummy', sampling_rate=sr)
 

bids/variables/variables.py

@@ -496,15 +496,20 @@ def split(self, grouper):
                                  source=self.source,
                                  sampling_rate=self.sampling_rate)
                 for i, name in enumerate(df.columns)]
-
-    def _build_entity_index(self, run_info, sampling_rate):
+        
+    def _build_entity_index(self, run_info, sampling_rate, match_vol=False):
         """Build the entity index from run information. """
 
         index = []
-        interval = int(round(1000. / sampling_rate))
         _timestamps = []
         for run in run_info:
-            reps = int(math.ceil(run.duration * sampling_rate))
+            if match_vol:
+                # If TR, fix reps to n_vols to ensure match
+                reps = run.n_vols
+            else:
+                reps = int(math.ceil(run.duration * sampling_rate))
+
+            interval = int(round(1000. / sampling_rate))            
             ent_vals = list(run.entities.values())
             df = pd.DataFrame([ent_vals] * reps, columns=list(run.entities.keys()))
             ts = pd.date_range(0, periods=len(df), freq='%sms' % interval)
@@ -532,14 +537,19 @@ def resample(self, sampling_rate, inplace=False, kind='linear'):
             var = self.clone()
             var.resample(sampling_rate, True, kind)
             return var
-
+
+        match_vol = False
+        if sampling_rate == 'TR':
+            match_vol = True
+            sampling_rate = 1. / self.run_info[0].tr
+
         if sampling_rate == self.sampling_rate:
             return
-
+        
         n = len(self.index)
 
-        self.index = self._build_entity_index(self.run_info, sampling_rate)
-
+        self.index = self._build_entity_index(self.run_info, sampling_rate, match_vol)
+        
         x = np.arange(n)
         num = len(self.index)