Added Labels element

holoviews/element/annotation.py

@@ -5,6 +5,8 @@
 from ..core.util import datetime_types, basestring
 from ..core import Dimension, Element2D
 
+from .chart import Points
+
 
 class Annotation(Element2D):
     """
@@ -251,3 +253,16 @@ def __init__(self, x, y, text, fontsize=12,
         super(Text, self).__init__(info, x=x, y=y, text=text,
                                    fontsize=fontsize, rotation=rotation,
                                    halign=halign, valign=valign, **params)
+
+
+class Labels(Points):
+    """
+    Labels represents a collection of text labels associated with 2D
+    coordinates. Unlike other Annotation types it is vectorized to
+    draw labels from a columnar dataset.
+    """
+
+    group = param.String(default='Labels', constant=True)
+
+    vdims = param.List([Dimension('Label')], bounds=(1, 1), doc="""
+        Defines the value dimension corresponding to the label text.""")

holoviews/plotting/bokeh/__init__.py

@@ -14,7 +14,7 @@
                         ErrorBars, Text, HLine, VLine, Spline, Spikes,
                         Table, ItemTable, Area, HSV, QuadMesh, VectorField,
                         Graph, Nodes, EdgePaths, Distribution, Bivariate,
-                        TriMesh, Violin, Chord)
+                        TriMesh, Violin, Chord, Labels)
 from ...core.options import Options, Cycle, Palette
 from ...core.util import VersionError
 
@@ -28,7 +28,8 @@
 except:
     DFrame = None
 
-from .annotation import TextPlot, LineAnnotationPlot, SplinePlot, ArrowPlot
+from .annotation import (LabelsPlot, TextPlot, LineAnnotationPlot,
+                         SplinePlot, ArrowPlot)
 from .callbacks import Callback # noqa (API import)
 from .element import OverlayPlot, ElementPlot
 from .chart import (PointPlot, CurvePlot, SpreadPlot, ErrorPlot, HistogramPlot,
@@ -90,6 +91,7 @@
                 HLine: LineAnnotationPlot,
                 VLine: LineAnnotationPlot,
                 Text: TextPlot,
+                Labels: LabelsPlot,
                 Spline: SplinePlot,
                 Arrow: ArrowPlot,
 

holoviews/plotting/bokeh/annotation.py

@@ -58,6 +58,32 @@ def get_extents(self, element, ranges=None):
 
 
 
+class LabelsPlot(ElementPlot):
+
+    style_opts = text_properties
+
+    _plot_methods = dict(single='text', batched='text')
+    _batched_style_opts = text_properties
+
+    def get_data(self, element, ranges=None, empty=False):
+        style = self.style[self.cyclic_index]
+        dims = element.dimensions(label=True)
+
+        xidx, yidx = (1, 0) if self.invert_axes else (0, 1)
+        mapping = dict(x=dims[xidx], y=dims[yidx])
+        data = {}
+
+        xdim, ydim = dims[xidx], dims[yidx]
+        data[xdim] = element.dimension_values(xidx)
+        data[ydim] = element.dimension_values(yidx)
+        self._categorize_data(data, (xdim, ydim), element.dimensions())
+
+        text_dim = dims[2]
+        data[text_dim] = element.dimension_values(text_dim)
+        return data, mapping
+
+
+
 class LineAnnotationPlot(ElementPlot):
 
     style_opts = line_properties

holoviews/plotting/mpl/__init__.py

@@ -169,6 +169,7 @@ def grid_selector(grid):
                 Arrow: ArrowPlot,
                 Spline: SplinePlot,
                 Text: TextPlot,
+                Labels: LabelsPlot,
 
                 # Path plots
                 Contours: ContourPlot,

holoviews/plotting/mpl/annotation.py

@@ -81,6 +81,30 @@ def draw_annotation(self, axis, data, opts):
                           rotation=rotation, **opts)]
 
 
+class LabelsPlot(ElementPlot):
+
+    style_opts = ['alpha', 'color', 'visible', 'linewidth',
+                  'linestyle', 'marker', 'ms']
+
+    _plot_methods = dict(single='annotate')
+
+    def get_data(self, element, ranges, style):
+        xs, ys = (element.dimension_values(i) for i in range(2))
+        text = element.dimension_values(2)
+        positions = (ys, xs) if self.invert_axes else (xs, ys)
+        return positions + (text,), style, {}
+
+    def init_artists(self, ax, plot_args, plot_kwargs):
+        texts = []
+        for x, y, text in zip(*plot_args):
+            texts.append(ax.text(x, y, text, **plot_kwargs))
+        return {'artist': texts}
+
+    def teardown_handles(self):
+        if 'artist' in self.handles:
+            for artist in self.handles['artist']:
+                artist.remove()
+
 
 class ArrowPlot(AnnotationPlot):
     "Draw an arrow using the information supplied to the Arrow annotation"