Add dtype methods to geometry interfaces (#345)

.travis.yml

@@ -15,10 +15,11 @@ before_cache:
 
 env:
   global:
-    - PYENV_VERSION=3.6
+    - PYENV_VERSION=3.7
+    - PYTHON_VERSION=3.6
     - PKG_TEST_PYTHON="--test-python=py36 --test-python=py27"
-    - CHANS_DEV="-c pyviz/label/dev -c ioam"
-    - CHANS_REL="-c pyviz -c ioam"
+    - CHANS_DEV="-c pyviz/label/dev"
+    - CHANS_REL="-c pyviz"
     - LABELS_DEV="--label dev"
     - LABELS_REL="--label dev --label main"
     - MPLBACKEND="Agg"
@@ -53,7 +54,7 @@ jobs:
         - conda config --set always_yes True
         - conda install -c pyviz "pyctdev>=0.5" && doit ecosystem_setup
       install:
-        - doit env_create $CHANS_DEV --python=$PYENV_VERSION
+        - doit env_create $CHANS_DEV --python=$PYTHON_VERSION
         - source activate test-environment
         - doit develop_install $CHANS_DEV -o recommended
         - doit env_capture
@@ -66,7 +67,7 @@ jobs:
     # python 2 flake checking typically catches python 2 syntax
     # errors where python 3's been assumed...
     - <<: *default
-      env: DESC="py2 flakes" PYENV_VERSION=2.7
+      env: DESC="py2 flakes" PYTHON_VERSION=2.7
       script: doit test_flakes
 
     ########## DOCS ##########

geoviews/data/geom_dict.py

@@ -74,6 +74,13 @@ def validate(cls, dataset, validate_vdims):
         assert len([d for d in dataset.kdims + dataset.vdims
                     if d.name not in dataset.data]) == 2
 
+    @classmethod
+    def dtype(cls, dataset, dimension):
+        name = dataset.get_dimension(dimension, strict=True).name
+        if name not in dataset.data:
+            return np.dtype('float') # Geometry dimension
+        return super(GeomDictInterface, cls).dtype(dataset, dimension)
+
     @classmethod
     def has_holes(cls, dataset):
         from shapely.geometry import Polygon, MultiPolygon

geoviews/data/geopandas.py

@@ -90,6 +90,15 @@ def validate(cls, dataset, vdims=True):
                              "dimensions, the following dimensions were "
                              "not found: %s" % repr(not_found), cls)
 
+
+    @classmethod
+    def dtype(cls, dataset, dimension):
+        name = dataset.get_dimension(dimension, strict=True).name
+        if name not in dataset.data:
+            return np.dtype('float') # Geometry dimension
+        return dataset.data[name].dtype
+
+
     @classmethod
     def has_holes(cls, dataset):
         from shapely.geometry import Polygon, MultiPolygon