Cleaned up .sample/.reduce API and fixed sanitization

Fixes issue #182

holoviews/core/dimension.py

@@ -584,7 +584,9 @@ def get_dimension_index(self, dim):
             else:
                 return IndexError('Dimension index out of bounds')
         try:
-            return [d.name for d in self.dimensions()].index(dim)
+            sanitized = {sanitize_identifier(kd): kd
+                         for kd in self._cached_index_names}
+            return [d.name for d in self.dimensions()].index(sanitized.get(dim, dim))
         except ValueError:
             raise Exception("Dimension %s not found in %s." %
                             (dim, self.__class__.__name__))

holoviews/core/element.py

@@ -10,7 +10,7 @@
 from .ndmapping import OrderedDict, UniformNdMapping, NdMapping, item_check
 from .overlay import Overlayable, NdOverlay, Overlay, CompositeOverlay
 from .tree import AttrTree
-
+from .util import sanitize_identifier
 
 class Element(ViewableElement, Composable, Overlayable):
     """
@@ -103,26 +103,41 @@ def closest(self, coords):
         return coords
 
 
-    def sample(self, **samples):
+    def sample(self, samples=[], **sample_values):
         """
-        Base class signature to demonstrate API for sampling Views.
-        To sample a ViewableElement kwargs, where the keyword matches a Dimension
-        in the ViewableElement and the value matches a corresponding entry in the
-        data.
+        Base class signature to demonstrate API for sampling Elements.
+        To sample an Element supply either a list of sampels or keyword
+        arguments, where the key should match an existing key dimension
+        on the Element.
         """
         raise NotImplementedError
 
 
-    def reduce(self, **reduce_map):
+    def reduce(self, dimensions=[], function=None, **reduce_map):
         """
         Base class signature to demonstrate API for reducing Elements,
         using some reduce function, e.g. np.mean, which is applied
         along a particular Dimension. The dimensions and reduce functions
-        should be passed as keyword arguments.
+        should be passed as keyword arguments or as a list of dimensions
+        and a single function.
         """
         raise NotImplementedError
 
 
+    def _reduce_map(self, dimensions, function, reduce_map):
+        dimensions = self._valid_dimensions(dimensions)
+        if dimensions and reduce_map:
+            raise Exception("Pass reduced dimensions either as an argument"
+                            "or as part of the kwargs not both.")
+        elif dimensions:
+            reduce_map = {dimensions[0]: function}
+        elif not reduce_map:
+            reduce_map = {d: function for d in self._cached_index_names}
+        sanitized = {sanitize_identifier(kd): kd
+                     for kd in self._cached_index_names}
+        return {sanitized.get(d, d): fn for d, fn in reduce_map.items()}
+
+
     def table(self, **kwargs):
         """
         This method transforms any ViewableElement type into a Table
@@ -333,12 +348,8 @@ def reduce(self, dimensions=None, function=None, **reduce_map):
         the dimension name and reduce_fn as kwargs. Reduces
         dimensionality of Table until only an ItemTable is left.
         """
-        dimensions = self._valid_dimensions(dimensions)
-        if dimensions and reduce_map:
-            raise Exception("Pass reduced dimensions either as an argument"
-                            "or as part of the kwargs not both.")
-        elif dimensions:
-            reduce_map = {d: function for d in dimensions}
+        reduce_map = self._reduce_map(dimensions, function, reduce_map)
+
         dim_labels = self._cached_index_names
         reduced_table = self
         for reduce_fn, group in groupby(reduce_map.items(), lambda x: x[1]):
@@ -667,6 +678,7 @@ def reduce(self, dimensions=None, function=None, **reduce_map):
                          for k, v in self.items()]
         return self.clone(reduced_items).table()
 
+
     def relabel(self, label=None, group=None, depth=1):
         # Identical to standard relabel method except for default depth of 1
         return super(HoloMap, self).relabel(label=label, group=group, depth=depth)

holoviews/element/chart.py

@@ -139,7 +139,7 @@ def collapse_data(cls, data, function, **kwargs):
 
     def sample(self, samples=[]):
         """
-        Allows sampling of Element2D objects using the default
+        Allows sampling of Chart Elements using the default
         syntax of providing a map of dimensions and sample pairs.
         """
         sample_data = OrderedDict()
@@ -158,14 +158,7 @@ def reduce(self, dimensions=[], function=None, **reduce_map):
         Allows collapsing of Chart objects using the supplied map of
         dimensions and reduce functions.
         """
-        dimensions = self._valid_dimensions(dimensions)
-        if dimensions and reduce_map:
-            raise Exception("Pass reduced dimensions either as an argument"
-                            "or as part of the kwargs not both.")
-        elif dimensions:
-            reduce_map = {dimensions[0]: function}
-        elif not reduce_map:
-            reduce_map = {d: function for d in self._cached_index_names}
+        reduce_map = self._reduce_map(dimensions, function, reduce_map)
 
         if len(reduce_map) > 1:
             raise ValueError("Chart Elements may only be reduced to a point.")
@@ -425,7 +418,7 @@ def dimension_values(self, dim):
             return super(Histogram, self).dimension_values(dim)
 
 
-    def sample(self, **samples):
+    def sample(self, samples=[], **sample_values):
         raise NotImplementedError('Cannot sample a Histogram.')
 
 

holoviews/element/raster.py

@@ -99,10 +99,12 @@ def sample(self, samples=[], **sample_values):
                 raise ValueError(
                     'Raster sampling requires coordinates not slices,'
                     'use regular slicing syntax.')
-            other_dimension = [d for d in self.kdims if
-                               d.name != dimension]
             # Indices inverted for indexing
             sample_ind = self.get_dimension_index(dimension)
+            if sample_ind is None:
+                raise Exception("Dimension %s not found during sampling" % dimension)
+            other_dimension = [d for i, d in enumerate(self.kdims) if
+                               i != sample_ind]
 
             # Generate sample slice
             sample = [slice(None) for i in range(self.ndims)]
@@ -123,15 +125,7 @@ def reduce(self, dimensions=None, function=None, **reduce_map):
         Optionally a label_prefix can be provided to prepend to
         the result Element label.
         """
-        dimensions = self._valid_dimensions(dimensions)
-        if dimensions and reduce_map:
-            raise Exception("Pass reduced dimensions either as an argument"
-                            "or as part of the kwargs not both.")
-        elif dimensions:
-            reduce_map = {d: function for d in dimensions}
-        elif not reduce_map:
-            reduce_map = {d: function for d in self._cached_index_names}
-
+        reduce_map = self._reduce_map(dimensions, function, reduce_map)
         if len(reduce_map) == self.ndims:
             reduced_view = self
             for dim, reduce_fn in reduce_map.items():

holoviews/interface/seaborn.py

@@ -59,11 +59,11 @@ def dimension_values(self, dimension):
             return super(TimeSeries, self).dimension_values(dimension)
 
 
-    def sample(self, **samples):
+    def sample(self, samples=[], **sample_values):
         raise NotImplementedError('Cannot sample a TimeSeries.')
 
 
-    def reduce(self, **dimreduce_map):
+    def reduce(self, dimensions=[], function=None, **reduce_map):
         raise NotImplementedError('Reduction of TimeSeries not '
                                   'implemented.')