Fix x ranges upon projection (#722)

Co-authored-by: Philipp Rudiger <[email protected]>

geoviews/plotting/bokeh/callbacks.py

@@ -64,6 +64,10 @@ def project_ranges(cb, msg, attributes):
     extents = x0, y0, x1, y1
     x0, y0, x1, y1 = project_extents(extents, plot.projection,
                                      plot.current_frame.crs)
+    if plot._unwrap_lons and -180 <= x0 < 0 or -180 <= x1 < 0:
+        x0, x1 = x0 + 360, x1 + 360
+        if x0 > x1:
+            x0, x1 = x1, x0
     coords = {'x_range': (x0, x1), 'y_range': (y0, y1)}
     return {k: v for k, v in coords.items() if k in attributes}
 

geoviews/plotting/bokeh/plot.py

@@ -3,7 +3,7 @@
 """
 import param
 
-from cartopy.crs import GOOGLE_MERCATOR, PlateCarree, Mercator
+from cartopy.crs import GOOGLE_MERCATOR, PlateCarree, Mercator, _CylindricalProjection
 from bokeh.models.tools import BoxZoomTool, WheelZoomTool
 from bokeh.models import MercatorTickFormatter, MercatorTicker, CustomJSHover
 from holoviews.core.dimension import Dimension
@@ -70,6 +70,8 @@ def __init__(self, element, **params):
                     'and disable the show_grid option.'
                 )
 
+        self._unwrap_lons = False
+
     def _axis_properties(self, axis, key, plot, dimension=None,
                          ax_mapping=None):
         if ax_mapping is None:
@@ -103,6 +105,11 @@ def _update_ranges(self, element, ranges):
                     ax_range.end = mid + min_interval/2.
                 ax_range.min_interval = min_interval
 
+    def _set_unwrap_lons(self, element):
+        if isinstance(self.geographic, _CylindricalProjection):
+            x1, x2 = element.range(0)
+            self._unwrap_lons = 0 <= x1 <= 360 and 0 <= x2 <= 360
+
     def initialize_plot(self, ranges=None, plot=None, plots=None, source=None):
         opts = {} if isinstance(self, HvOverlayPlot) else {'source': source}
         fig = super().initialize_plot(ranges, plot, plots, **opts)
@@ -113,8 +120,14 @@ def initialize_plot(self, ranges=None, plot=None, plots=None, source=None):
                                      overlaid=True, renderer=self.renderer)
             shapeplot.geographic = False
             shapeplot.initialize_plot(plot=fig)
+        self._set_unwrap_lons(self.current_frame)
         return fig
 
+    def update_frame(self, key, ranges=None, element=None):
+        if element is not None:
+            self._set_unwrap_lons(element)
+        super().update_frame(key, ranges, element)
+
     def _postprocess_hover(self, renderer, source):
         super()._postprocess_hover(renderer, source)
         hover = self.handles["plot"].hover

geoviews/tests/test_operation.py

@@ -14,3 +14,40 @@ def test_quadmesh_contoures_filled():
     p1 = gv.QuadMesh(ds, kdims=["lon", "lat"])
     p2 = contours(p1, filled=True)
     gv.renderer("bokeh").get_plot(p2)
+
+
+def test_unwrap_lons():
+    pytest.importorskip("datashader")
+    # Regression test for: https://github.com/holoviz/geoviews/pull/722
+    from holoviews.operation.datashader import rasterize
+    ds = xr.tutorial.open_dataset("air_temperature").isel(time=0)
+    p1 = gv.Image(ds)
+    p2 = rasterize(p1, filled=True)
+    gv.renderer("bokeh").get_plot(p2)
+    for x in p2.range(0):
+        assert x >= 0
+        assert x <= 360
+    p2.callback()
+    for x in p2.range(0):
+        assert x >= 0
+        assert x <= 360
+
+
+def test_no_unwrap_lons():
+    pytest.importorskip("datashader")
+    # Regression test for: https://github.com/holoviz/geoviews/pull/722
+    from holoviews.operation.datashader import rasterize
+    ds = xr.tutorial.open_dataset("air_temperature").isel(time=0)
+    # to -180, 180
+    ds["lon"] = (ds["lon"] + 180) % 360 - 180
+
+    p1 = gv.Image(ds)
+    p2 = rasterize(p1, filled=True)
+    gv.renderer("bokeh").get_plot(p2)
+    for x in p2.range(0):
+        assert x >= -180
+        assert x <= 180
+    p2.callback()
+    for x in p2.range(0):
+        assert x >= -180
+        assert x <= 180