Various fixes for datashader

holoviews/operation/datashader.py

@@ -114,7 +114,8 @@ def instance(self_or_cls,**params):
         inst._precomputed = {}
         return inst
 
-    def _get_sampling(self, element, x, y):
+
+    def _get_sampling(self, element, x, y, ndim=2, default=None):
         target = self.p.target
         if not isinstance(x, list) and x is not None:
             x = [x]
@@ -128,7 +129,8 @@ def _get_sampling(self, element, x, y):
         else:
             if x is None:
                 x_range = self.p.x_range or (-0.5, 0.5)
-                y_range = self.p.y_range or (-0.5, 0.5)
+            elif self.p.expand or not self.p.x_range:
+                x_range = self.p.x_range or max_range([element.range(xd) for xd in x])
             else:
                 x0, x1 = self.p.x_range
                 ex0, ex1 = max_range([element.range(xd) for xd in x])
@@ -145,18 +147,9 @@ def _get_sampling(self, element, x, y):
                 if default is None:
                     ey0, ey1 = max_range([element.range(yd) for yd in y])
                 else:
-                    x0, x1 = self.p.x_range
-                    ex0, ex1 = element.range(x)
-                    x_range = (np.min([np.max([x0, ex0]), ex1]),
-                               np.max([np.min([x1, ex1]), ex0]))
-
-                if self.p.expand or not self.p.y_range:
-                    y_range = self.p.y_range or element.range(y)
-                else:
-                    y0, y1 = self.p.y_range
-                    ey0, ey1 = element.range(y)
-                    y_range = (np.min([np.max([y0, ey0]), ey1]),
-                               np.max([np.min([y1, ey1]), ey0]))
+                    ey0, ey1 = default
+                y_range = (np.min([np.max([y0, ey0]), ey1]),
+                           np.max([np.min([y1, ey1]), ey0]))
             width, height = self.p.width, self.p.height
         (xstart, xend), (ystart, yend) = x_range, y_range
 
@@ -168,7 +161,6 @@ def _get_sampling(self, element, x, y):
             xstart, xend = 0, 0
             if x and element.get_dimension_type(x[0]) in datetime_types:
                 xtype = 'datetime'
-        x_range = (xstart, xend)
 
         ytype = 'numeric'
         if isinstance(ystart, datetime_types) or isinstance(yend, datetime_types):
@@ -178,7 +170,6 @@ def _get_sampling(self, element, x, y):
             ystart, yend = 0, 0
             if y and element.get_dimension_type(y[0]) in datetime_types:
                 ytype = 'datetime'
-        y_range = (ystart, yend)
 
         # Compute highest allowed sampling density
         xspan = xend - xstart
@@ -198,7 +189,18 @@ def _get_sampling(self, element, x, y):
         xs, ys = (np.linspace(xstart+xunit/2., xend-xunit/2., width),
                   np.linspace(ystart+yunit/2., yend-yunit/2., height))
 
-        return (x_range, y_range), (xs, ys), (width, height), (xtype, ytype)
+        return ((xstart, xend), (ystart, yend)), (xs, ys), (width, height), (xtype, ytype)
+
+
+    def _dt_transform(self, x_range, y_range, xs, ys, xtype, ytype):
+        (xstart, xend), (ystart, yend) = x_range, y_range
+        if xtype == 'datetime':
+            xstart, xend = (np.array([xstart, xend])/1e3).astype('datetime64[us]')
+            xs = (xs/1e3).astype('datetime64[us]')
+        if ytype == 'datetime':
+            ystart, yend = (np.array([ystart, yend])/1e3).astype('datetime64[us]')
+            ys = (ys/1e3).astype('datetime64[us]')
+        return ((xstart, xend), (ystart, yend)), (xs, ys)
 
 
 
@@ -260,6 +262,43 @@ def _get_aggregator(self, element, add_field=True):
         return agg
 
 
+    def _empty_agg(self, element, x, y, width, height, xs, ys, agg_fn, **params):
+        x = x.name if x else 'x'
+        y = y.name if x else 'y'
+        xarray = xr.DataArray(np.full((height, width), np.NaN),
+                              dims=[y, x], coords={x: xs, y: ys})
+        if width == 0:
+            params['xdensity'] = 1
+        if height == 0:
+            params['ydensity'] = 1
+        el = self.p.element_type(xarray, **params)
+        if isinstance(agg_fn, ds.count_cat):
+            vals = element.dimension_values(agg_fn.column, expanded=False)
+            dim = element.get_dimension(agg_fn.column)
+            return NdOverlay({v: el for v in vals}, dim)
+        return el
+
+
+    def _get_agg_params(self, element, x, y, agg_fn, bounds):
+        params = dict(get_param_values(element), kdims=[x, y],
+                      datatype=['xarray'], bounds=bounds)
+
+        column = agg_fn.column if agg_fn else None
+        if column:
+            dims = [d for d in element.dimensions('ranges') if d == column]
+            if not dims:
+                raise ValueError("Aggregation column %s not found on %s element. "
+                                 "Ensure the aggregator references an existing "
+                                 "dimension." % (column,element))
+            name = '%s Count' % column if isinstance(agg_fn, ds.count_cat) else column
+            vdims = [dims[0].clone(name)]
+        else:
+            vdims = Dimension('Count')
+        params['vdims'] = vdims
+        return params
+
+
+
 class aggregate(AggregationOperation):
     """
     aggregate implements 2D binning for any valid HoloViews Element