Datetime64 fixes

holoviews/core/data/__init__.py

@@ -463,7 +463,7 @@ def get_dimension_type(self, dim):
         dim_obj = self.get_dimension(dim)
         if dim_obj and dim_obj.type is not None:
             return dim_obj.type
-        return self.interface.dimension_type(self, dim)
+        return self.interface.dimension_type(self, dim_obj)
 
 
     def dframe(self, dimensions=None):

holoviews/core/data/grid.py

@@ -84,10 +84,8 @@ def validate(cls, dataset):
 
     @classmethod
     def dimension_type(cls, dataset, dim):
-        if dim in dataset.kdims:
-            arr = dataset.data[dim.name]
-        elif dim in dataset.vdims:
-            arr = dataset.data[dim.name]
+        if dim in dataset.dimensions():
+            arr = cls.values(dataset, dim, False, False)
         else:
             return None
         return arr.dtype.type

holoviews/core/data/xarray.py

@@ -78,7 +78,10 @@ def range(cls, dataset, dimension):
         dim = dataset.get_dimension(dimension).name
         if dim in dataset.data:
             data = dataset.data[dim]
-            return data.min().item(), data.max().item()
+            dmin, dmax = data.min().data, data.max().data
+            dmin = dmin if np.isscalar(dmin) else dmin.item()
+            dmax = dmax if np.isscalar(dmax) else dmax.item()
+            return dmin, dmax
         else:
             return np.NaN, np.NaN
 

holoviews/plotting/mpl/chart.py

@@ -1,18 +1,20 @@
 from __future__ import unicode_literals
+
 from itertools import product
 
 import numpy as np
 from matplotlib import cm
 from matplotlib import pyplot as plt
 from matplotlib.collections import LineCollection
+from matplotlib.dates import date2num
 
 import param
 
 from ...core import OrderedDict
 from ...core.util import (match_spec, unique_iterator, safe_unicode,
                           basestring, max_range, unicode)
 from ...element import Points, Raster, Polygons, HeatMap
-from ..util import compute_sizes, get_sideplot_ranges
+from ..util import compute_sizes, get_sideplot_ranges, dt64_to_dt
 from .element import ElementPlot, ColorbarPlot, LegendPlot
 from .path  import PathPlot
 from .plot import AdjoinedPlot
@@ -61,6 +63,14 @@ def get_data(self, element, ranges, style):
         ys = element.dimension_values(1)
         return (xs, ys), style, {}
 
+    def init_artists(self, ax, plot_args, plot_kwargs):
+        xs, ys = plot_args
+        if xs.dtype.kind == 'M':
+            xs = np.array([date2num(dt64_to_dt(x)) for x in xs])
+            artist = ax.plot_date(xs, ys, '-', **plot_kwargs)[0]
+        else:
+            artist = ax.plot(xs, ys, **plot_kwargs)[0]
+        return {'artist': artist}
 
     def update_handles(self, key, axis, element, ranges, style):
         artist = self.handles['artist']

holoviews/plotting/mpl/element.py

@@ -1,4 +1,5 @@
 import math
+import datetime as dt
 
 from matplotlib import ticker
 from matplotlib import colors
@@ -302,6 +303,8 @@ def _set_axis_limits(self, axis, view, subplots, ranges):
         extents = self.get_extents(view, ranges)
         if extents and not self.overlaid:
             coords = [coord if np.isreal(coord) else np.NaN for coord in extents]
+            coords = [c.astype(dt.datetime) if isinstance(c, np.datetime64) else c
+                      for c in coords]
             valid_lim = lambda c: util.isnumeric(c) and not np.isnan(c)
             if self.projection == '3d' or len(extents) == 6:
                 l, b, zmin, r, t, zmax = coords

holoviews/plotting/util.py

@@ -1,5 +1,7 @@
 from __future__ import unicode_literals
 
+from datetime import datetime as dt
+
 import numpy as np
 import param
 
@@ -270,3 +272,10 @@ def dim_axis_label(dimensions, separator=', '):
     if not isinstance(dimensions, list): dimensions = [dimensions]
     return separator.join([safe_unicode(d.pprint_label)
                            for d in dimensions])
+
+def dt64_to_dt(dt64):
+    """
+    Safely converts NumPy datetime64 to a datetime object.
+    """
+    ts = (dt64 - np.datetime64('1970-01-01T00:00:00Z')) / np.timedelta64(1, 's')
+    return dt.utcfromtimestamp(ts)