Fix some of the coordinate classes for the case of single coordinates…

… to be APE 14-compliant

glue/core/coordinate_helpers.py

@@ -59,8 +59,7 @@ def pixel2world_single_axis(wcs, *pixel, world_axis=None):
 
     if len(pixel) == 1 and pixel[0].ndim > 1:
         pixel_shape = pixel[0].shape
-        pixel = [pixel[0].ravel()]
-        result = wcs.pixel_to_world_values(*pixel)
+        result = wcs.pixel_to_world_values(pixel[0].ravel())
         result = result.reshape(pixel_shape)
     else:
         result = wcs.pixel_to_world_values(*pixel)
@@ -112,9 +111,21 @@ def world2pixel_single_axis(wcs, *world, pixel_axis=None):
             world_new.append(w.flat[0])
     world = np.broadcast_arrays(*world_new)
 
-    result = wcs.world_to_pixel_values(*world)
+    # In the case of 1D WCS, there is an astropy issue which prevents us from
+    # passing arbitrary shapes - see https://github.com/astropy/astropy/issues/12154
+    # Therefore, we ravel the values and reshape afterwards
+
+    if len(world) == 1 and world[0].ndim > 1:
+        world_shape = world[0].shape
+        result = wcs.world_to_pixel_values(world[0].ravel())
+        result = result.reshape(world_shape)
+    else:
+        result = wcs.world_to_pixel_values(*world)
+
+    if len(world) > 1:
+        result = result[pixel_axis]
 
-    return np.broadcast_to(result[pixel_axis], original_shape)
+    return np.broadcast_to(result, original_shape)
 
 
 def world_axis(wcs, data, *, pixel_axis=None, world_axis=None):

glue/core/coordinates.py

@@ -90,10 +90,16 @@ def __init__(self):
         super().__init__(pixel_n_dim=10, world_n_dim=10)
 
     def pixel_to_world_values(self, *pixel):
-        return pixel
+        if self.pixel_n_dim == 1:
+            return pixel[0]
+        else:
+            return pixel
 
     def world_to_pixel_values(self, *world):
-        return world
+        if self.world_n_dim == 1:
+            return world[0]
+        else:
+            return world
 
 
 class IdentityCoordinates(Coordinates):
@@ -102,10 +108,16 @@ def __init__(self, n_dim=None):
         super().__init__(pixel_n_dim=n_dim, world_n_dim=n_dim)
 
     def pixel_to_world_values(self, *pixel):
-        return pixel
+        if self.pixel_n_dim == 1:
+            return pixel[0]
+        else:
+            return pixel
 
     def world_to_pixel_values(self, *world):
-        return world
+        if self.world_n_dim == 1:
+            return world[0]
+        else:
+            return world
 
     @property
     def axis_correlation_matrix(self):

glue/core/tests/test_data.py

@@ -818,10 +818,16 @@ def world_axis_names(self):
             return ['Custom {0}'.format(axis) for axis in range(3)]
 
         def world_to_pixel_values(self, *world):
-            return tuple([0.4 * w for w in world])
+            if self.pixel_n_dim == 1:
+                return 0.4 * world[0]
+            else:
+                return tuple([0.4 * w for w in world])
 
         def pixel_to_world_values(self, *pixel):
-            return tuple([2.5 * p for p in pixel])
+            if self.world_n_dim == 1:
+                return 2.5 * pixel[0]
+            else:
+                return tuple([2.5 * p for p in pixel])
 
     data1.coords = CustomCoordinates()
 

glue/core/tests/test_links.py

@@ -19,6 +19,7 @@ def test_1d_world_link():
     dc.add_link(LinkSame(d2.world_component_ids[0], d1.id['x']))
 
     assert d2.world_component_ids[0] in d1.externally_derivable_components
+
     np.testing.assert_array_equal(d1[d2.world_component_ids[0]], x)
     np.testing.assert_array_equal(d1[d2.pixel_component_ids[0]], x)