Add VectorField project operation

geoviews/operation/projection.py

@@ -154,7 +154,7 @@ def _process_element(self, element):
 
 class project_points(_project_operation):
 
-    supported_types = [Points, Nodes, VectorField, HexTiles, Labels]
+    supported_types = [Points, Nodes, HexTiles, Labels]
 
     def _process_element(self, element):
         if not len(element):
@@ -181,6 +181,44 @@ def _process_element(self, element):
                              crs=self.p.projection, datatype=datatype)
 
 
+class project_vectorfield(_project_operation):
+
+    supported_types = [VectorField]
+
+    def _process_element(self, element):
+        if not len(element):
+            return element.clone(crs=self.p.projection)
+        xdim, ydim, adim, mdim = element.dimensions()[:4]
+        xs, ys, ang, ms = (element.dimension_values(i) for i in range(4))
+        coordinates = self.p.projection.transform_points(element.crs, xs, ys)
+        mask = np.isfinite(coordinates[:, 0])
+        new_data = {k: v[mask] for k, v in element.columns().items()}
+        new_data[xdim.name] = coordinates[mask, 0]
+        new_data[ydim.name] = coordinates[mask, 1]
+        datatype = [element.interface.datatype]+element.datatype
+        us = np.sin(ang) * ms
+        vs = np.cos(ang) * ms
+        ut, vt = self.p.projection.transform_vectors(element.crs, xs, ys, us, vs)
+        with np.errstate(divide='ignore', invalid='ignore'):
+            angle = np.arctan2(vt, ut)
+        mag = np.sqrt(ut**2+vt**2)
+
+        new_data[adim.name] = angle[mask]
+        new_data[mdim.name] = mag[mask]
+
+        if len(new_data[xdim.name]) == 0:
+            self.warning('While projecting a %s element from a %s coordinate '
+                         'reference system (crs) to a %s projection none of '
+                         'the projected paths were contained within the bounds '
+                         'specified by the projection. Ensure you have specified '
+                         'the correct coordinate system for your data.' %
+                         (type(element).__name__, type(element.crs).__name__,
+                          type(self.p.projection).__name__))
+
+        return element.clone(tuple(new_data[d.name] for d in element.dimensions()),
+                             crs=self.p.projection, datatype=datatype)
+
+
 
 class project_graph(_project_operation):
 
@@ -392,7 +430,8 @@ class project(Operation):
         Projection the image type is projected to.""")
 
     _operations = [project_path, project_image, project_shape,
-                   project_graph, project_quadmesh, project_points]
+                   project_graph, project_quadmesh, project_vectorfield,
+                   project_points]
 
     def _process(self, element, key=None):
         for op in self._operations:

geoviews/plotting/bokeh/__init__.py

@@ -20,7 +20,7 @@
                         Graph, TriMesh, QuadMesh, VectorField, Labels,
                         HexTiles, LineContours, FilledContours)
 from ...operation import (project_image, project_points, project_path,
-                          project_graph, project_quadmesh)
+                          project_graph, project_quadmesh, project_vectorfield)
 from ...tile_sources import _ATTRIBUTIONS
 from ...util import poly_types, line_types
 from .plot import GeoPlot, GeoOverlayPlot
@@ -91,7 +91,7 @@ class GeoPointPlot(GeoPlot, PointPlot):
 
 class GeoVectorFieldPlot(GeoPlot, VectorFieldPlot):
 
-    _project_operation = project_points
+    _project_operation = project_vectorfield
 
 
 class GeoQuadMeshPlot(GeoPlot, QuadMeshPlot):

geoviews/plotting/mpl/__init__.py

@@ -23,15 +23,17 @@
 from holoviews.plotting.mpl.util import get_raster_array
 
 
-from ...element import (Image, Points, Feature, WMTS, Tiles, Text,
-                        LineContours, FilledContours, is_geographic,
-                        Path, Polygons, Shape, RGB, Contours, Nodes,
-                        EdgePaths, Graph, TriMesh, QuadMesh, VectorField,
-                        HexTiles, Labels)
+from ...element import (
+    Image, Points, Feature, WMTS, Tiles, Text, LineContours,
+    FilledContours, is_geographic, Path, Polygons, Shape, RGB,
+    Contours, Nodes, EdgePaths, Graph, TriMesh, QuadMesh, VectorField,
+    HexTiles, Labels)
 from ...util import geo_mesh
 from ..plot import ProjectionPlot
 
-from ...operation import project_points, project_path, project_graph, project_quadmesh
+from ...operation import (
+    project_points, project_path, project_graph, project_quadmesh,
+    project_vectorfield)
 
 
 
@@ -238,7 +240,7 @@ class GeoVectorFieldPlot(GeoPlot, VectorFieldPlot):
 
     apply_ranges = param.Boolean(default=True)
 
-    _project_operation = project_points
+    _project_operation = project_vectorfield
 
 
 class GeometryPlot(GeoPlot):