RF: make exposed ArraySequence.data return a copy

Author: MarcCote

nibabel/streamlines/array_sequence.py

@@ -1,5 +1,6 @@
 
 import numbers
+import warnings
 from operator import mul
 from functools import reduce
 
@@ -147,7 +148,22 @@ def total_nb_rows(self):
     @property
     def data(self):
         """ Elements in this array sequence. """
-        return self._data
+        warnings.warn("The 'ArraySequence.data' property has been deprecated"
+                      " in favor of 'ArraySequence.get_data()'.",
+                      DeprecationWarning,
+                      stacklevel=2)
+        return self.get_data()
+
+    def get_data(self):
+        """ Returns a copy of the elements in this array sequence.
+
+        Notes
+        -----
+        To modify the data on this array sequence, one can use
+        in-place mathematical operators (e.g., `seq += ...`) or the use
+        assignment operator (i.e, `seq[...] = value`).
+        """
+        return self.copy()._data
 
     def _check_shape(self, arrseq):
         """ Check whether this array sequence is compatible with another. """

nibabel/streamlines/tests/test_array_sequence.py

@@ -441,6 +441,15 @@ def test_save_and_load_arraysequence(self):
             # Make sure we can add new elements to it.
             loaded_seq.append(SEQ_DATA['data'][0])
 
+    def test_get_data(self):
+        seq_view = SEQ_DATA['seq'][::2]
+        check_arr_seq_view(seq_view, SEQ_DATA['seq'])
+
+        # We make sure the array sequence data does not
+        # contain more elements than it is supposed to.
+        data = seq_view.get_data()
+        assert len(data) < len(seq_view._data)
+
 
 def test_concatenate():
     seq = SEQ_DATA['seq'].copy()  # In case there is in-place modification.