Properly update world components if Data.coords is set and world comp…

…onents already exist

glue/core/data.py

@@ -72,8 +72,7 @@ def __init__(self, label="", coords=None, **kwargs):
 
         Extra array-like keywords are extracted into components
         """
-        # Coordinate conversion object
-        self.coords = coords or Coordinates()
+
         self._shape = ()
 
         # Components
@@ -83,6 +82,9 @@ def __init__(self, label="", coords=None, **kwargs):
         self._pixel_component_ids = ComponentIDList()
         self._world_component_ids = ComponentIDList()
 
+        # Coordinate conversion object
+        self.coords = coords or Coordinates()
+
         self.id = ComponentIDDict(self)
 
         # Metadata
@@ -113,6 +115,19 @@ def __init__(self, label="", coords=None, **kwargs):
         # uniquely identify them.
         self.uuid = str(uuid.uuid4())
 
+    @property
+    def coords(self):
+        """
+        The coordinates object for the data.
+        """
+        return self._coords
+
+    @coords.setter
+    def coords(self, value):
+        self._coords = value
+        if len(self.components) > 0:
+            self._update_world_components(self.ndim)
+
     @property
     def subsets(self):
         """
@@ -545,14 +560,21 @@ def add_component_link(self, link, label=None):
         return dc
 
     def _create_pixel_and_world_components(self, ndim):
+        self._update_pixel_components(ndim)
+        self._update_world_components(ndim)
 
+    def _update_pixel_components(self, ndim):
         for i in range(ndim):
             comp = CoordinateComponent(self, i)
             label = pixel_label(i, ndim)
             cid = PixelComponentID(i, "Pixel Axis %s" % label, parent=self)
             self.add_component(comp, cid)
             self._pixel_component_ids.append(cid)
 
+    def _update_world_components(self, ndim):
+        for cid in self._world_component_ids[:]:
+            self.remove_component(cid)
+            self._world_component_ids.remove(cid)
         if self.coords:
             for i in range(ndim):
                 comp = CoordinateComponent(self, i, world=True)

glue/core/tests/test_data.py

@@ -4,6 +4,7 @@
 
 import pytest
 import numpy as np
+from numpy.testing import assert_equal
 from mock import MagicMock
 
 from glue.external import six
@@ -785,3 +786,34 @@ class CustomObject(object):
     assert data2.meta['a'] == 1
     assert data2.meta['b'] == 'test'
     assert 'c' not in data2.meta
+
+
+def test_update_coords():
+
+    # Make sure that when overriding coords, the world coordinate components
+    # are updated.
+
+    data = Data(x=[1, 2, 3])
+
+    assert len(data.components) == 3
+
+    assert_equal(data[data.world_component_ids[0]], [0, 1, 2])
+
+    class CustomCoordinates(Coordinates):
+
+        def axis_label(self, axis):
+            return 'Custom {0}'.format(axis)
+
+        def world2pixel(self, *world):
+            return tuple([0.4 * w for w in world])
+
+        def pixel2world(self, *pixel):
+            return tuple([2.5 * p for p in pixel])
+
+    data.coords = CustomCoordinates()
+
+    assert len(data.components) == 3
+
+    assert_equal(data[data.world_component_ids[0]], [0, 2.5, 5])
+
+    assert sorted(cid.label for cid in data.world_component_ids) == ['Custom 0']