Improved legends and tick labels on Bars

holoviews/plotting/chart.py

@@ -11,7 +11,7 @@
 from ..core import OrderedDict, NdMapping, ViewableElement, CompositeOverlay, HoloMap
 from ..core.util import match_spec
 from ..element import Scatter, Curve, Histogram, Bars, Points, Raster, VectorField, ErrorBars, Polygons
-from .element import ElementPlot
+from .element import ElementPlot, LegendPlot
 from .plot import MPLPlot
 
 
@@ -735,7 +735,7 @@ def update_handles(self, axis, view, key, ranges=None):
             quiver.set_clim(ranges[magnitude_dim])
 
 
-class BarPlot(ElementPlot):
+class BarPlot(LegendPlot):
 
     group_index = param.Integer(default=0, doc="""
        Index of the dimension in the supplied Bars
@@ -764,6 +764,13 @@ class BarPlot(ElementPlot):
     style_opts = ['alpha', 'color', 'align', 'visible', 'edgecolor',
                   'log', 'facecolor', 'capsize', 'error_kw', 'hatch']
 
+    legend_specs = dict(LegendPlot.legend_specs, **{
+        'top':    dict(bbox_to_anchor=(0., 1.02, 1., .102),
+                       ncol=3, loc=3, mode="expand", borderaxespad=0.),
+        'bottom': dict(ncol=3, mode="expand", loc=2,
+                       bbox_to_anchor=(0., -0.4, 1., .102),
+                       borderaxespad=0.1)})
+
     _dimensions = OrderedDict([('group', 0),
                                ('category',1),
                                ('stack',2)])
@@ -833,22 +840,17 @@ def initialize_plot(self, ranges=None):
         ranges = match_spec(element, ranges)
         dims = element.dimensions('key', label=True)
 
-        self.handles['bars'], xticks = self._create_bars(axis, element)
+        self.handles['bars'], xticks, xlabel = self._create_bars(axis, element)
         self.handles['legend_handle'] = self.handles['bars']
-        self._set_ticks(axis, dims, xticks)
-        return self._finalize_axis(key, ranges=ranges, ylabel=str(vdim))
+        return self._finalize_axis(key, ranges=ranges, xticks=xticks, xlabel=xlabel, ylabel=str(vdim))
 
 
-    def _set_ticks(self, axis, dims, xticks):
+    def _finalize_ticks(self, axis, xticks, yticks, zticks):
         """
         Apply ticks with appropriate offsets.
         """
-        ndims = len(dims)
-        idx = self.group_index if self.group_index < ndims else self.category_index
         ticks, labels, yalignments = zip(*sorted(xticks, key=lambda x: x[0]))
-        axis.set_xlabel(dims[idx], labelpad=-0.15 if idx < ndims else -0.05)
-        axis.set_xticks(ticks)
-        axis.set_xticklabels(labels)
+        super(BarPlot, self)._finalize_ticks(axis, [ticks, labels], yticks, zticks)
         for t, y in zip(axis.get_xticklabels(), yalignments):
             t.set_y(y)
 
@@ -864,6 +866,7 @@ def _create_bars(self, axis, element):
         style_opts, color_groups, sopts = self._compute_styles(element, style_groups)
         dims = element.dimensions('key', label=True)
         ndims = len(dims)
+        xlabel = ' / '.join([str(d) for d in [cdim, gdim] if d is not None])
 
         # Compute widths
         width = (1-(2.*self.padding)) / len(values['category'])
@@ -886,8 +889,7 @@ def _create_bars(self, axis, element):
                     style_key[idx] = grp_name
                 val_key[gi] = grp_name
                 if ci < ndims:
-                    yalign = -0.125
-                    xticks.append((gidx+0.5, dims[ci], -0.05))
+                    yalign = -0.04
                 else:
                     yalign = 0
                 xticks.append((gidx+0.5, grp_name, yalign))
@@ -921,9 +923,11 @@ def _create_bars(self, axis, element):
                     labels.append(label)
         title = [str(element.kdims[indices[cg]])
                  for cg in self.color_by if indices[cg] < ndims]
-        if any(len(l) for l in labels):
-            axis.legend(title=', '.join(title))
-        return bars, xticks
+        if self.show_legend and any(len(l) for l in labels):
+            leg_spec = self.legend_specs[self.legend_position]
+            if self.legend_cols: leg_spec['ncol'] = self.legend_cols
+            axis.legend(title=', '.join(title), **leg_spec)
+        return bars, xticks, xlabel
 
 
     def update_handles(self, axis, element, key, ranges=None):

holoviews/plotting/element.py

@@ -495,38 +495,46 @@ def update_handles(self, axis, view, key, ranges=None):
         raise NotImplementedError
 
 
-class OverlayPlot(ElementPlot):
-    """
-    OverlayPlot supports compositors processing of Overlays across maps.
-    """
-
-    style_grouping = param.Integer(default=2,
-                                   doc="""The length of the type.group.label
-        spec that will be used to group Elements into style groups, i.e.
-        a style_grouping value of 1 will group just by type, a value of 2
-        will group by type and group and a value of 3 will group by the
-        full specification.""")
+class LegendPlot(ElementPlot):
 
     show_legend = param.Boolean(default=True, doc="""
         Whether to show legend for the plot.""")
 
+    legend_cols = param.Integer(default=None, doc="""
+       Number of legend columns in the legend.""")
+
     legend_position = param.ObjectSelector(objects=['inner', 'right',
                                                     'bottom', 'top',
-                                                    'left'],
+                                                    'left', 'best'],
                                            default='inner', doc="""
         Allows selecting between a number of predefined legend position
         options. The predefined options may be customized in the
         legend_specs class attribute.""")
 
     legend_specs = {'inner': {},
-                    'left':   dict(bbox_to_anchor=(-.15, 1)),
-                    'right':  dict(bbox_to_anchor=(1.25, 1)),
+                    'best': {},
+                    'left':   dict(bbox_to_anchor=(-.15, 1), loc=1),
+                    'right':  dict(bbox_to_anchor=(1.05, 1), loc=2),
                     'top':    dict(bbox_to_anchor=(0., 1.02, 1., .102),
-                                   ncol=3, mode="expand", borderaxespad=0.),
-                    'bottom': dict(ncol=3, mode="expand",
+                                   ncol=3, loc=3, mode="expand", borderaxespad=0.),
+                    'bottom': dict(ncol=3, mode="expand", loc=2,
                                    bbox_to_anchor=(0., -0.25, 1., .102),
                                    borderaxespad=0.1)}
 
+
+
+class OverlayPlot(LegendPlot):
+    """
+    OverlayPlot supports compositors processing of Overlays across maps.
+    """
+
+    style_grouping = param.Integer(default=2,
+                                   doc="""The length of the type.group.label
+        spec that will be used to group Elements into style groups, i.e.
+        a style_grouping value of 1 will group just by type, a value of 2
+        will group by type and group and a value of 3 will group by the
+        full specification.""")
+
     def __init__(self, overlay, ranges=None, **params):
         super(OverlayPlot, self).__init__(overlay, ranges=ranges, **params)
 
@@ -642,6 +650,7 @@ def _adjust_legend(self, axis):
                 legend.set_visible(False)
         else:
             leg_spec = self.legend_specs[self.legend_position]
+            if self.legend_cols: leg_spec['ncol'] = self.legend_cols
             leg = axis.legend(data.keys(), data.values(),
                               title=title, scatterpoints=1,
                               **leg_spec)