[field,geom] Support changing grid dim order

phi/field/_field.py

@@ -348,7 +348,12 @@ def with_boundary(self, boundary):
 
     def with_bounds(self, bounds: Box):
         """ Returns a copy of this field with `bounds` replaced. """
-        return Field(self._geometry, self._values, self._boundary)
+        order = list(bounds.vector.item_names)
+        geometry = self._geometry.vector[order]
+        geometry[order]
+        new_shape = self._values.shape.without(order) & self._values.shape.only(order, reorder=True)
+        values = math.transpose(self._values, new_shape)
+        return Field(geometry, values, self._boundary)
 
     def with_geometry(self, elements: Geometry):
         """ Returns a copy of this field with `elements` replaced. """

phi/geom/_grid.py

@@ -147,7 +147,10 @@ def __getitem__(self, item):
                 bounds = Box(lower, upper)
                 gather_dict[dim] = slice(start, stop)
         resolution = self._resolution.after_gather(gather_dict)
-        return UniformGrid(resolution, bounds[{d: s for d, s in item.items() if d != 'vector'}])
+        bounds = bounds[{d: s for d, s in item.items() if d != 'vector'}]
+        if 'vector' in item:
+            bounds = bounds[item['vector']]  # resolution[item['vector']] will be done automatically
+        return UniformGrid(resolution, bounds)
 
     def __pack_dims__(self, dims: Tuple[str, ...], packed_dim: Shape, pos: Optional[int], **kwargs) -> 'Cuboid':
         return math.pack_dims(self.center_representation(), dims, packed_dim, pos, **kwargs)