FIX: Accept any valid delimiters/EOF markers in TCK files

nibabel/cifti2/cifti2.py

@@ -287,7 +287,7 @@ def rgba(self):
         return (self.red, self.green, self.blue, self.alpha)
 
     def _to_xml_element(self):
-        if self.label is '':
+        if self.label == '':
             raise Cifti2HeaderError('Label needs a name')
         try:
             v = int(self.key)

nibabel/streamlines/tck.py

@@ -390,18 +390,14 @@ def _read(cls, fileobj, header, buffer_size=4):
         buffer_size = int(buffer_size * MEGABYTE)
         buffer_size += coordinate_size - (buffer_size % coordinate_size)
 
-        # Markers for streamline end and file end
-        fiber_marker = cls.FIBER_DELIMITER.astype(dtype).tostring()
-        eof_marker = cls.EOF_DELIMITER.astype(dtype).tostring()
-
         with Opener(fileobj) as f:
             start_position = f.tell()
 
             # Set the file position at the beginning of the data.
             f.seek(header["_offset_data"], os.SEEK_SET)
 
             eof = False
-            buffs = []
+            leftover = np.empty((0, 3), dtype='<f4')
             n_streams = 0
 
             while not eof:
@@ -411,37 +407,36 @@ def _read(cls, fileobj, header, buffer_size=4):
                 if eof:
                     buff = buff[:n_read]
 
-                buffs.append(buff)
-
-                # Make sure we've read enough to find a streamline delimiter.
-                if fiber_marker not in buff:
-                    # If we've read the whole file, then fail.
-                    if eof:
-                        # Could have minimal buffering, and have read only the
-                        # EOF delimiter
-                        buffs = [bytearray().join(buffs)]
-                        if not buffs[0] == eof_marker:
-                            raise DataError(
-                                "Cannot find a streamline delimiter. This file"
-                                " might be corrupted.")
-                    else:
-                        # Otherwise read a bit more.
-                        continue
-
-                all_parts = bytearray().join(buffs).split(fiber_marker)
-                point_parts, buffs = all_parts[:-1], all_parts[-1:]
-                point_parts = [p for p in point_parts if p != b'']
-
-                for point_part in point_parts:
-                    # Read floats.
-                    pts = np.frombuffer(point_part, dtype=dtype)
-                    # Convert data to little-endian if needed.
-                    yield pts.astype('<f4', copy=False).reshape([-1, 3])
-
-                n_streams += len(point_parts)
-
-            if not buffs[-1] == eof_marker:
-                raise DataError("Expecting end-of-file marker 'inf inf inf'")
+                raw_values = np.frombuffer(buff, dtype=dtype)
+
+                # Convert raw_values into a list of little-endian triples (for x,y,z coord)
+                coords = raw_values.astype('<f4', copy=False).reshape((-1, 3))
+
+                # Find stream delimiter locations (all NaNs)
+                delims = np.where(np.isnan(coords).all(axis=1))[0]
+
+                # Recover leftovers, which can't have delimiters in them
+                if leftover.size:
+                    delims += leftover.shape[0]
+                    coords = np.vstack((leftover, coords))
+
+                begin = 0
+                for delim in delims:
+                    pts = coords[begin:delim]
+                    if pts.size:
+                        yield pts
+                        n_streams += 1
+                    begin = delim + 1
+
+                # The rest becomes the new leftover.
+                leftover = coords[begin:]
+
+            if not (leftover.shape == (1, 3) and np.isinf(leftover).all()):
+                if n_streams == 0:
+                    msg = "Cannot find a streamline delimiter. This file might be corrupted."
+                else:
+                    msg = "Expecting end-of-file marker 'inf inf inf'"
+                raise DataError(msg)
 
             # In case the 'count' field was not provided.
             header[Field.NB_STREAMLINES] = n_streams

nibabel/streamlines/tests/test_tck.py

@@ -32,6 +32,7 @@ def setup():
                                                 "simple_big_endian.tck")
     # standard.tck contains only streamlines
     DATA['standard_tck_fname'] = pjoin(data_path, "standard.tck")
+    DATA['matlab_nan_tck_fname'] = pjoin(data_path, "matlab_nan.tck")
 
     DATA['streamlines'] = [np.arange(1 * 3, dtype="f4").reshape((1, 3)),
                            np.arange(2 * 3, dtype="f4").reshape((2, 3)),
@@ -64,6 +65,13 @@ def test_load_simple_file(self):
         tck = TckFile(tractogram, header=hdr)
         assert_tractogram_equal(tck.tractogram, DATA['simple_tractogram'])
 
+    def test_load_matlab_nan_file(self):
+        for lazy_load in [False, True]:
+            tck = TckFile.load(DATA['matlab_nan_tck_fname'], lazy_load=lazy_load)
+            streamlines = list(tck.tractogram.streamlines)
+            assert_equal(len(streamlines), 1)
+            assert_equal(streamlines[0].shape, (108, 3))
+
     def test_writeable_data(self):
         data = DATA['simple_tractogram']
         for key in ('simple_tck_fname', 'simple_tck_big_endian_fname'):