From b7d37b856f9240688fe11b65f72e2c9cc42b1267 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Fri, 25 May 2018 02:50:26 +0100
Subject: [PATCH 01/14] Added support for cftime types

---
 holoviews/core/data/xarray.py       | 11 +++++++++++
 holoviews/plotting/bokeh/element.py |  4 +++-
 holoviews/plotting/bokeh/plot.py    | 25 +++++++++++++++++++++----
 holoviews/plotting/bokeh/util.py    |  9 +++++----
 4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/holoviews/core/data/xarray.py b/holoviews/core/data/xarray.py
index ae7394f33c..cac57018a7 100644
--- a/holoviews/core/data/xarray.py
+++ b/holoviews/core/data/xarray.py
@@ -12,6 +12,17 @@
 from .grid import GridInterface
 from .interface import Interface, DataError, dask_array_module
 
+try:
+    import cftime
+    util.datetime_types += (
+        cftime._cftime.DatetimeGregorian,
+        cftime._cftime.Datetime360Day,
+        cftime._cftime.DatetimeJulian,
+        cftime._cftime.DatetimeNoLeap,
+        cftime._cftime.DatetimeProlepticGregorian)
+except:
+    pass
+
 
 class XArrayInterface(GridInterface):
 
diff --git a/holoviews/plotting/bokeh/element.py b/holoviews/plotting/bokeh/element.py
index b0e3364771..210243893b 100644
--- a/holoviews/plotting/bokeh/element.py
+++ b/holoviews/plotting/bokeh/element.py
@@ -40,7 +40,7 @@
 from .util import (
     bokeh_version, decode_bytes, get_tab_title, glyph_order,
     py2js_tickformatter, recursive_model_update, theme_attr_json,
-    cds_column_replace, hold_policy, match_dim_specs
+    cds_column_replace, hold_policy, match_dim_specs, date_to_integer
 )
 
 
@@ -634,6 +634,8 @@ def _update_range(self, axis_range, low, high, factors, invert, shared, log, str
                 if reset_supported:
                     updates['reset_end'] = updates['end']
             for k, (old, new) in updates.items():
+                if isinstance(new, util.datetime_types):
+                    new = date_to_integer(new)
                 axis_range.update(**{k:new})
                 if streaming and not k.startswith('reset_'):
                     axis_range.trigger(k, old, new)
diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index ab1d675d6d..66bcdb9bd1 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -11,12 +11,13 @@
 from bokeh.models import (ColumnDataSource, Column, Row, Div)
 from bokeh.models.widgets import Panel, Tabs
 from bokeh.plotting.helpers import _known_tools as known_tools
+from bokeh.util.serialization import convert_datetime_array
 
 from ...core import (OrderedDict, Store, AdjointLayout, NdLayout, Layout,
                      Empty, GridSpace, HoloMap, Element, DynamicMap)
 from ...core.options import SkipRendering
 from ...core.util import (basestring, wrap_tuple, unique_iterator,
-                          get_method_owner, wrap_tuple_streams)
+                          get_method_owner, datetime_types, wrap_tuple_streams)
 from ...streams import Stream
 from ..links import Link
 from ..plot import (DimensionedPlot, GenericCompositePlot, GenericLayoutPlot,
@@ -25,7 +26,7 @@
 from .callbacks import LinkCallback
 from .util import (layout_padding, pad_plots, filter_toolboxes, make_axis,
                    update_shared_sources, empty_plot, decode_bytes,
-                   theme_attr_json, cds_column_replace)
+                   theme_attr_json, cds_column_replace, date_to_integer)
 
 TOOLS = {name: tool if isinstance(tool, basestring) else type(tool())
          for name, tool in known_tools.items()}
@@ -226,10 +227,26 @@ def _init_datasource(self, data):
         """
         Initializes a data source to be passed into the bokeh glyph.
         """
-        data = {k: decode_bytes(vs) for k, vs in data.items()}
+        data = self._postprocess_data(data)
         return ColumnDataSource(data=data)
 
 
+    def _postprocess_data(self, data):
+        """
+        Applies necessary type transformation to the data before
+        it is set on a ColumnDataSource.
+        """
+        new_data = {}
+        for k, values in data.items():
+            values = decode_bytes(values) # Bytes need decoding to strings
+
+            # Certain datetime types need to be converted
+            if len(values) and isinstance(values[0], datetime_types):
+                values = np.array([date_to_integer(v) for v in values])
+            new_data[k] = values
+        return new_data
+
+
     def _update_datasource(self, source, data):
         """
         Update datasource with data for a new frame.
@@ -237,7 +254,7 @@ def _update_datasource(self, source, data):
         if not self.document:
             return
 
-        data = {k: decode_bytes(vs) for k, vs in data.items()}
+        data = self._postprocess_data(data)
         empty = all(len(v) == 0 for v in data.values())
         if (self.streaming and self.streaming[0].data is self.current_frame.data
             and self._stream_data and not empty):
diff --git a/holoviews/plotting/bokeh/util.py b/holoviews/plotting/bokeh/util.py
index 145bd9a75e..5c95c3f6dd 100644
--- a/holoviews/plotting/bokeh/util.py
+++ b/holoviews/plotting/bokeh/util.py
@@ -3,6 +3,7 @@
 import re
 import time
 import sys
+import calendar
 import datetime as dt
 
 from collections import defaultdict
@@ -542,10 +543,10 @@ def date_to_integer(date):
     """
     if isinstance(date, np.datetime64):
         date = dt64_to_dt(date)
-    if pd and isinstance(date, pd.Timestamp):
-        dt_int = date.timestamp()*1000
-    elif isinstance(date, (dt.datetime, dt.date)):
-        dt_int = time.mktime(date.timetuple())*1000
+    elif pd and isinstance(date, pd.Timestamp):
+        date = date.to_pydatetime()
+    if hasattr(date, 'timetuple'):
+        dt_int = calendar.timegm(date.timetuple())*1000
     else:
         raise ValueError('Datetime type not recognized')
     return dt_int

From 5ec1e7d9a82d30220b9a346f97313170b0b0f5e9 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Mon, 3 Dec 2018 18:27:11 +0000
Subject: [PATCH 02/14] Minor fix so NdMapping allows cftimes types as keys

---
 holoviews/core/ndmapping.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/core/ndmapping.py b/holoviews/core/ndmapping.py
index 067b44068d..121899fde4 100644
--- a/holoviews/core/ndmapping.py
+++ b/holoviews/core/ndmapping.py
@@ -650,7 +650,7 @@ def __getitem__(self, indexslice):
             return self.data[()]
         elif indexslice in [Ellipsis, ()]:
             return self
-        elif Ellipsis in wrap_tuple(indexslice):
+        elif any(Ellipsis is sl for sl in wrap_tuple(indexslice)):
             indexslice = process_ellipses(self, indexslice)
 
         map_slice, data_slice = self._split_index(indexslice)

From 88bebf399eca1b99e395f3bf8807b7163e6d78bc Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Wed, 5 Dec 2018 13:02:17 +0000
Subject: [PATCH 03/14] Add support for nc_time_axis in matplotlib backend

---
 holoviews/core/data/xarray.py  |  8 +++++---
 holoviews/plotting/mpl/util.py | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/holoviews/core/data/xarray.py b/holoviews/core/data/xarray.py
index cac57018a7..03fa9f2284 100644
--- a/holoviews/core/data/xarray.py
+++ b/holoviews/core/data/xarray.py
@@ -14,14 +14,16 @@
 
 try:
     import cftime
-    util.datetime_types += (
+    cftime_types = (
         cftime._cftime.DatetimeGregorian,
         cftime._cftime.Datetime360Day,
         cftime._cftime.DatetimeJulian,
         cftime._cftime.DatetimeNoLeap,
-        cftime._cftime.DatetimeProlepticGregorian)
+        cftime._cftime.DatetimeProlepticGregorian
+    )
+    util.datetime_types += cftime_types
 except:
-    pass
+    cftime_types = ()
 
 
 class XArrayInterface(GridInterface):
diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index 6b37961211..c4be4d6ea1 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -5,6 +5,7 @@
 
 import numpy as np
 import matplotlib
+from matplotlib import units as munits
 from matplotlib import ticker
 from matplotlib.colors import cnames
 from matplotlib.lines import Line2D
@@ -14,6 +15,8 @@
 from matplotlib.rcsetup import (
     validate_capstyle, validate_fontsize, validate_fonttype, validate_hatch,
     validate_joinstyle)
+
+from ...core.data.xarray import cftime_types
 from ...core.util import LooseVersion, _getargspec, basestring, is_number
 from ...element import Raster, RGB, Polygons
 from ..util import COLOR_ALIASES, RGB_HEX_REGEX
@@ -334,3 +337,34 @@ def polygons_to_path_patches(element):
             subpath.append(PathPatch(Path(vertices, codes)))
         mpl_paths.append(subpath)
     return mpl_paths
+
+try:
+    if cftime_types:
+        from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
+    else:
+        import matplotlib.dates import DateConverter
+        NetCDFTimeConverter = DateConverter
+    nc_axis_available = True
+except:
+    import matplotlib.dates import DateConverter
+    NetCDFTimeConverter = DateConverter
+    nc_axis_available = False
+
+class CFTimeConverter(NetCDFTimeConverter):
+
+    @classmethod
+    def convert(cls, value, unit, axis):
+        if not nc_axis_available:
+            raise ValueError('In order to display cftime types with '
+                             'matplotlib install the nc_time_axis '
+                             'library using pip or from conda-forge '
+                             'using:\n\tconda install -c conda-forge '
+                             'nc_time_axis')
+        if isinstance(value, cftime_types):
+            value = CalendarDateTime(cftime.datetime(*value.timetuple()[0:6]), value.calendar)
+        elif isinstance(value, np.ndarray):
+            value = np.array([CalendarDateTime(cftime.datetime(*v.timetuple()[0:6]), v.calendar) for v in value])
+        return super(CFTimeConverter, cls).convert(value, unit, axis)
+
+for cft in cftime_types:
+    munits.registry[cft] = CFTimeConverter()

From 8b71267d2628d1b8f712862f208595d9fb6df160 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Wed, 5 Dec 2018 16:41:34 +0000
Subject: [PATCH 04/14] Fixed flakes

---
 holoviews/plotting/bokeh/plot.py | 1 -
 holoviews/plotting/mpl/util.py   | 9 +++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index 66bcdb9bd1..640c3e43b1 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -11,7 +11,6 @@
 from bokeh.models import (ColumnDataSource, Column, Row, Div)
 from bokeh.models.widgets import Panel, Tabs
 from bokeh.plotting.helpers import _known_tools as known_tools
-from bokeh.util.serialization import convert_datetime_array
 
 from ...core import (OrderedDict, Store, AdjointLayout, NdLayout, Layout,
                      Empty, GridSpace, HoloMap, Element, DynamicMap)
diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index c4be4d6ea1..1847cbec15 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -342,15 +342,19 @@ def polygons_to_path_patches(element):
     if cftime_types:
         from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
     else:
-        import matplotlib.dates import DateConverter
+        from matplotlib.dates import DateConverter
         NetCDFTimeConverter = DateConverter
     nc_axis_available = True
 except:
-    import matplotlib.dates import DateConverter
+    from matplotlib.dates import DateConverter
     NetCDFTimeConverter = DateConverter
     nc_axis_available = False
 
+
 class CFTimeConverter(NetCDFTimeConverter):
+    """
+    Defines conversions for cftime types by extending nc_time_axis.
+    """
 
     @classmethod
     def convert(cls, value, unit, axis):
@@ -366,5 +370,6 @@ def convert(cls, value, unit, axis):
             value = np.array([CalendarDateTime(cftime.datetime(*v.timetuple()[0:6]), v.calendar) for v in value])
         return super(CFTimeConverter, cls).convert(value, unit, axis)
 
+
 for cft in cftime_types:
     munits.registry[cft] = CFTimeConverter()

From eb3f0c8032da0b1ddc6eb707ed057e8d4555a708 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Wed, 5 Dec 2018 17:16:35 +0000
Subject: [PATCH 05/14] Further cftime fix

---
 holoviews/plotting/mpl/util.py | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index 1847cbec15..45d612cc5d 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -339,11 +339,8 @@ def polygons_to_path_patches(element):
     return mpl_paths
 
 try:
-    if cftime_types:
-        from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
-    else:
-        from matplotlib.dates import DateConverter
-        NetCDFTimeConverter = DateConverter
+    import cftime
+    from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
     nc_axis_available = True
 except:
     from matplotlib.dates import DateConverter

From 155cd82322e5a09b5e9950d4ca60599f6202711d Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 02:34:04 +0000
Subject: [PATCH 06/14] Improved handling of cftimes in bokeh

---
 holoviews/plotting/bokeh/element.py |  7 ++--
 holoviews/plotting/bokeh/plot.py    | 31 +++++++++++------
 holoviews/plotting/bokeh/util.py    | 52 ++++++++++++++++++++++++-----
 holoviews/plotting/mpl/element.py   |  6 ++--
 4 files changed, 72 insertions(+), 24 deletions(-)

diff --git a/holoviews/plotting/bokeh/element.py b/holoviews/plotting/bokeh/element.py
index 210243893b..39a1f2cfa8 100644
--- a/holoviews/plotting/bokeh/element.py
+++ b/holoviews/plotting/bokeh/element.py
@@ -25,6 +25,7 @@
 from bokeh.plotting.helpers import _known_tools as known_tools
 
 from ...core import DynamicMap, CompositeOverlay, Element, Dimension
+from ...core.data.xarray import cftime_types
 from ...core.options import abbreviated_exception, SkipRendering
 from ...core import util
 from ...element import Graph, VectorField, Path, Contours
@@ -606,7 +607,9 @@ def _update_ranges(self, element, ranges):
 
     def _update_range(self, axis_range, low, high, factors, invert, shared, log, streaming=False):
         if isinstance(axis_range, (Range1d, DataRange1d)) and self.apply_ranges:
-            if (low == high and low is not None):
+            if isinstance(low, cftime_types):
+                pass
+            elif (low == high and low is not None):
                 if isinstance(low, util.datetime_types):
                     offset = np.timedelta64(500, 'ms')
                     low -= offset
@@ -634,7 +637,7 @@ def _update_range(self, axis_range, low, high, factors, invert, shared, log, str
                 if reset_supported:
                     updates['reset_end'] = updates['end']
             for k, (old, new) in updates.items():
-                if isinstance(new, util.datetime_types):
+                if isinstance(new, cftime_types):
                     new = date_to_integer(new)
                 axis_range.update(**{k:new})
                 if streaming and not k.startswith('reset_'):
diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index 640c3e43b1..3659a5f4ad 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -12,20 +12,29 @@
 from bokeh.models.widgets import Panel, Tabs
 from bokeh.plotting.helpers import _known_tools as known_tools
 
-from ...core import (OrderedDict, Store, AdjointLayout, NdLayout, Layout,
-                     Empty, GridSpace, HoloMap, Element, DynamicMap)
+from ...core import (
+    OrderedDict, Store, AdjointLayout, NdLayout, Layout, Empty,
+    GridSpace, HoloMap, Element, DynamicMap
+)
+from ...core.data.xarray import cftime_types
 from ...core.options import SkipRendering
-from ...core.util import (basestring, wrap_tuple, unique_iterator,
-                          get_method_owner, datetime_types, wrap_tuple_streams)
+from ...core.util import (
+    basestring, wrap_tuple, unique_iterator, get_method_owner,
+    datetime_types, wrap_tuple_streams)
+
 from ...streams import Stream
 from ..links import Link
-from ..plot import (DimensionedPlot, GenericCompositePlot, GenericLayoutPlot,
-                    GenericElementPlot, GenericOverlayPlot)
+from ..plot import (
+    DimensionedPlot, GenericCompositePlot, GenericLayoutPlot,
+    GenericElementPlot, GenericOverlayPlot
+)
 from ..util import attach_streams, displayable, collate
 from .callbacks import LinkCallback
-from .util import (layout_padding, pad_plots, filter_toolboxes, make_axis,
-                   update_shared_sources, empty_plot, decode_bytes,
-                   theme_attr_json, cds_column_replace, date_to_integer)
+from .util import (
+    layout_padding, pad_plots, filter_toolboxes, make_axis,
+    update_shared_sources, empty_plot, decode_bytes, theme_attr_json,
+    cds_column_replace, cftime_to_timestamp
+)
 
 TOOLS = {name: tool if isinstance(tool, basestring) else type(tool())
          for name, tool in known_tools.items()}
@@ -240,8 +249,8 @@ def _postprocess_data(self, data):
             values = decode_bytes(values) # Bytes need decoding to strings
 
             # Certain datetime types need to be converted
-            if len(values) and isinstance(values[0], datetime_types):
-                values = np.array([date_to_integer(v) for v in values])
+            if len(values) and isinstance(values[0], cftime_types):
+                values = cftime_to_timestamp(values)
             new_data[k] = values
         return new_data
 
diff --git a/holoviews/plotting/bokeh/util.py b/holoviews/plotting/bokeh/util.py
index 5c95c3f6dd..9e224cb75e 100644
--- a/holoviews/plotting/bokeh/util.py
+++ b/holoviews/plotting/bokeh/util.py
@@ -31,6 +31,7 @@
 except:
     Chart = type(None) # Create stub for isinstance check
 
+from ...core.data.xarray import cftime_types
 from ...core.overlay import Overlay
 from ...core.util import (LooseVersion, _getargspec, basestring,
                           callable_name, dt64_to_dt, pd, unique_array)
@@ -209,10 +210,6 @@ def make_axis(axis, size, factors, dim, flip=False, rotation=0,
     return p
 
 
-def convert_datetime(time):
-    return time.astype('datetime64[s]').astype(float)*1000
-
-
 def hsv_to_rgb(hsv):
     """
     Vectorized HSV to RGB conversion, adapted from:
@@ -537,14 +534,51 @@ def append_refresh(dmap):
     return plot.hmap.traverse(append_refresh, [DynamicMap])
 
 
-def date_to_integer(date):
+def cftime_to_timestamp(date):
+    """Converts cftime to timestamp since epoch in milliseconds
+
+    Non-standard calendars (e.g. Julian or no leap calendars)
+    are converted to standard Gregorian calendar. This can cause
+    extra space to be added for dates that don't exist in the original
+    calendar. In order to handle these dates correctly a custom bokeh
+    model with support for other calendars would have to be defind.
+
+    Args:
+        date: cftime datetime object (or array)
+
+    Returns:
+        Milliseconds since 1970-01-01 00:00:00
     """
-    Converts datetime types to bokeh's integer format.
+    import cftime
+    utime = cftime.utime('days since 1970-01-01')
+    return utime.date2num(date)*86400000
+
+
+def date_to_integer(date):
+    """Converts support date types to milliseconds since epoch
+
+    Attempts highest precision conversion of different datetime
+    formats to milliseconds since the epoch (1970-01-01 00:00:00).
+    If datetime is a cftime with a non-standard calendar the
+    caveats describd in cftime_to_timestamp apply.
+
+    Args:
+        date: Date- or datetime-like object
+
+    Returns:
+        Milliseconds since 1970-01-01 00:00:00
     """
+    if pd and isinstance(date, pd.Timestamp):
+        try:
+            date = date.to_datetime64()
+        except:
+            date = date.to_datetime()
+
     if isinstance(date, np.datetime64):
-        date = dt64_to_dt(date)
-    elif pd and isinstance(date, pd.Timestamp):
-        date = date.to_pydatetime()
+        return time.astype('datetime64[ms]').astype(float)
+    elif isinstance(date, cftime_types):
+        return cftime_to_timestamp(date)
+
     if hasattr(date, 'timetuple'):
         dt_int = calendar.timegm(date.timetuple())*1000
     else:
diff --git a/holoviews/plotting/mpl/element.py b/holoviews/plotting/mpl/element.py
index 0e59114239..ab7548e9ba 100644
--- a/holoviews/plotting/mpl/element.py
+++ b/holoviews/plotting/mpl/element.py
@@ -14,6 +14,7 @@
 from ...core import util
 from ...core import (OrderedDict, NdOverlay, DynamicMap, Dataset,
                      CompositeOverlay, Element3D, Element)
+from ...core.data.xarray import cftime_types
 from ...core.options import abbreviated_exception
 from ...element import Graph, Path, Contours
 from ...util.transform import dim
@@ -331,7 +332,8 @@ def _set_axis_limits(self, axis, view, subplots, ranges):
 
             if self.invert_xaxis or any(p.invert_xaxis for p in subplots):
                 r, l = l, r
-            if l != r:
+
+            if isinstance(l, cftime_types) or l != r:
                 lims = {}
                 if valid_lim(l):
                     lims['left'] = l
@@ -343,7 +345,7 @@ def _set_axis_limits(self, axis, view, subplots, ranges):
                     axis.set_xlim(**lims)
             if self.invert_yaxis or any(p.invert_yaxis for p in subplots):
                 t, b = b, t
-            if b != t:
+            if isinstance(b, cftime_types) or b != t:
                 lims = {}
                 if valid_lim(b):
                     lims['bottom'] = b

From 180117ae8bb88feca9b7d9ae3718875c539aaae8 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 03:00:00 +0000
Subject: [PATCH 07/14] Reorganized code

---
 holoviews/core/data/xarray.py       | 13 ---------
 holoviews/core/util.py              | 45 +++++++++++++++++++++++++++--
 holoviews/plotting/bokeh/element.py |  5 ++--
 holoviews/plotting/bokeh/plot.py    |  8 ++---
 holoviews/plotting/bokeh/util.py    | 26 ++---------------
 holoviews/plotting/mpl/element.py   |  5 ++--
 holoviews/plotting/mpl/util.py      | 22 +++++++-------
 7 files changed, 64 insertions(+), 60 deletions(-)

diff --git a/holoviews/core/data/xarray.py b/holoviews/core/data/xarray.py
index 03fa9f2284..ae7394f33c 100644
--- a/holoviews/core/data/xarray.py
+++ b/holoviews/core/data/xarray.py
@@ -12,19 +12,6 @@
 from .grid import GridInterface
 from .interface import Interface, DataError, dask_array_module
 
-try:
-    import cftime
-    cftime_types = (
-        cftime._cftime.DatetimeGregorian,
-        cftime._cftime.Datetime360Day,
-        cftime._cftime.DatetimeJulian,
-        cftime._cftime.DatetimeNoLeap,
-        cftime._cftime.DatetimeProlepticGregorian
-    )
-    util.datetime_types += cftime_types
-except:
-    cftime_types = ()
-
 
 class XArrayInterface(GridInterface):
 
diff --git a/holoviews/core/util.py b/holoviews/core/util.py
index c85c2096b7..c5e7d21f60 100644
--- a/holoviews/core/util.py
+++ b/holoviews/core/util.py
@@ -92,6 +92,19 @@ def __cmp__(self, other):
 except ImportError:
     pd = None
 
+try:
+    import cftime
+    cftime_types = (
+        cftime._cftime.DatetimeGregorian,
+        cftime._cftime.Datetime360Day,
+        cftime._cftime.DatetimeJulian,
+        cftime._cftime.DatetimeNoLeap,
+        cftime._cftime.DatetimeProlepticGregorian
+    )
+    datetime_types += cftime_types
+except:
+    cftime_types = ()
+
 
 class VersionError(Exception):
     "Raised when there is a library version mismatch."
@@ -1805,8 +1818,12 @@ def dt_to_int(value, time_unit='us'):
         if isinstance(value, pd.Period):
             value = value.to_timestamp()
         if isinstance(value, pd.Timestamp):
-            value = value.to_pydatetime()
-        value = np.datetime64(value)
+            try:
+                value = value.to_datetime64()
+            except:
+                value = np.datetime64(value.to_pydatetime())
+    elif isinstance(value, cftime_types):
+        return cftime_to_timestamp(value, time_unit)
 
     if isinstance(value, np.datetime64):
         value = np.datetime64(value, 'ns')
@@ -1833,6 +1850,30 @@ def dt_to_int(value, time_unit='us'):
         return (time.mktime(value.timetuple()) + value.microsecond / 1e6) * tscale
 
 
+def cftime_to_timestamp(date, time_unit='us'):
+    """Converts cftime to timestamp since epoch in milliseconds
+
+    Non-standard calendars (e.g. Julian or no leap calendars)
+    are converted to standard Gregorian calendar. This can cause
+    extra space to be added for dates that don't exist in the original
+    calendar. In order to handle these dates correctly a custom bokeh
+    model with support for other calendars would have to be defind.
+
+    Args:
+        date: cftime datetime object (or array)
+
+    Returns:
+        Milliseconds since 1970-01-01 00:00:00
+    """
+    import cftime
+    utime = cftime.utime('microseconds since 1970-01-01')
+    if time_unit == 'us':
+        tscale = 1
+    else:
+        tscale = (np.timedelta64(1, time_unit)/np.timedelta64(1, 'us')) * 1000.
+    return utime.date2num(date)*tscale
+
+
 def search_indices(values, source):
     """
     Given a set of values returns the indices of each of those values
diff --git a/holoviews/plotting/bokeh/element.py b/holoviews/plotting/bokeh/element.py
index 39a1f2cfa8..f944c1bd50 100644
--- a/holoviews/plotting/bokeh/element.py
+++ b/holoviews/plotting/bokeh/element.py
@@ -25,7 +25,6 @@
 from bokeh.plotting.helpers import _known_tools as known_tools
 
 from ...core import DynamicMap, CompositeOverlay, Element, Dimension
-from ...core.data.xarray import cftime_types
 from ...core.options import abbreviated_exception, SkipRendering
 from ...core import util
 from ...element import Graph, VectorField, Path, Contours
@@ -607,7 +606,7 @@ def _update_ranges(self, element, ranges):
 
     def _update_range(self, axis_range, low, high, factors, invert, shared, log, streaming=False):
         if isinstance(axis_range, (Range1d, DataRange1d)) and self.apply_ranges:
-            if isinstance(low, cftime_types):
+            if isinstance(low, util.cftime_types):
                 pass
             elif (low == high and low is not None):
                 if isinstance(low, util.datetime_types):
@@ -637,7 +636,7 @@ def _update_range(self, axis_range, low, high, factors, invert, shared, log, str
                 if reset_supported:
                     updates['reset_end'] = updates['end']
             for k, (old, new) in updates.items():
-                if isinstance(new, cftime_types):
+                if isinstance(new, util.cftime_types):
                     new = date_to_integer(new)
                 axis_range.update(**{k:new})
                 if streaming and not k.startswith('reset_'):
diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index 3659a5f4ad..3eebf86692 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -16,12 +16,10 @@
     OrderedDict, Store, AdjointLayout, NdLayout, Layout, Empty,
     GridSpace, HoloMap, Element, DynamicMap
 )
-from ...core.data.xarray import cftime_types
 from ...core.options import SkipRendering
 from ...core.util import (
-    basestring, wrap_tuple, unique_iterator, get_method_owner,
-    datetime_types, wrap_tuple_streams)
-
+    basestring, cftime_to_timestamp, cftime_types, datetime_types,
+    get_method_owner, unique_iterator, wrap_tuple, wrap_tuple_streams)
 from ...streams import Stream
 from ..links import Link
 from ..plot import (
@@ -33,7 +31,7 @@
 from .util import (
     layout_padding, pad_plots, filter_toolboxes, make_axis,
     update_shared_sources, empty_plot, decode_bytes, theme_attr_json,
-    cds_column_replace, cftime_to_timestamp
+    cds_column_replace
 )
 
 TOOLS = {name: tool if isinstance(tool, basestring) else type(tool())
diff --git a/holoviews/plotting/bokeh/util.py b/holoviews/plotting/bokeh/util.py
index 9e224cb75e..1e1ebbe50a 100644
--- a/holoviews/plotting/bokeh/util.py
+++ b/holoviews/plotting/bokeh/util.py
@@ -31,10 +31,10 @@
 except:
     Chart = type(None) # Create stub for isinstance check
 
-from ...core.data.xarray import cftime_types
 from ...core.overlay import Overlay
-from ...core.util import (LooseVersion, _getargspec, basestring,
-                          callable_name, dt64_to_dt, pd, unique_array)
+from ...core.util import (
+    LooseVersion, _getargspec, basestring, callable_name, cftime_types,
+    cftime_to_timestamp, dt64_to_dt, pd, unique_array)
 from ...core.spaces import get_nested_dmaps, DynamicMap
 from ..util import dim_axis_label
 
@@ -534,26 +534,6 @@ def append_refresh(dmap):
     return plot.hmap.traverse(append_refresh, [DynamicMap])
 
 
-def cftime_to_timestamp(date):
-    """Converts cftime to timestamp since epoch in milliseconds
-
-    Non-standard calendars (e.g. Julian or no leap calendars)
-    are converted to standard Gregorian calendar. This can cause
-    extra space to be added for dates that don't exist in the original
-    calendar. In order to handle these dates correctly a custom bokeh
-    model with support for other calendars would have to be defind.
-
-    Args:
-        date: cftime datetime object (or array)
-
-    Returns:
-        Milliseconds since 1970-01-01 00:00:00
-    """
-    import cftime
-    utime = cftime.utime('days since 1970-01-01')
-    return utime.date2num(date)*86400000
-
-
 def date_to_integer(date):
     """Converts support date types to milliseconds since epoch
 
diff --git a/holoviews/plotting/mpl/element.py b/holoviews/plotting/mpl/element.py
index ab7548e9ba..87689a7924 100644
--- a/holoviews/plotting/mpl/element.py
+++ b/holoviews/plotting/mpl/element.py
@@ -14,7 +14,6 @@
 from ...core import util
 from ...core import (OrderedDict, NdOverlay, DynamicMap, Dataset,
                      CompositeOverlay, Element3D, Element)
-from ...core.data.xarray import cftime_types
 from ...core.options import abbreviated_exception
 from ...element import Graph, Path, Contours
 from ...util.transform import dim
@@ -333,7 +332,7 @@ def _set_axis_limits(self, axis, view, subplots, ranges):
             if self.invert_xaxis or any(p.invert_xaxis for p in subplots):
                 r, l = l, r
 
-            if isinstance(l, cftime_types) or l != r:
+            if isinstance(l, util.cftime_types) or l != r:
                 lims = {}
                 if valid_lim(l):
                     lims['left'] = l
@@ -345,7 +344,7 @@ def _set_axis_limits(self, axis, view, subplots, ranges):
                     axis.set_xlim(**lims)
             if self.invert_yaxis or any(p.invert_yaxis for p in subplots):
                 t, b = b, t
-            if isinstance(b, cftime_types) or b != t:
+            if isinstance(b, util.cftime_types) or b != t:
                 lims = {}
                 if valid_lim(b):
                     lims['bottom'] = b
diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index 45d612cc5d..d1a71191d8 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -16,8 +16,17 @@
     validate_capstyle, validate_fontsize, validate_fonttype, validate_hatch,
     validate_joinstyle)
 
-from ...core.data.xarray import cftime_types
-from ...core.util import LooseVersion, _getargspec, basestring, is_number
+try:
+    import cftime
+    from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
+    nc_axis_available = True
+except:
+    from matplotlib.dates import DateConverter
+    NetCDFTimeConverter = DateConverter
+    nc_axis_available = False
+
+from ...core.util import (
+    LooseVersion, _getargspec, basestring, cftime_types, is_number)
 from ...element import Raster, RGB, Polygons
 from ..util import COLOR_ALIASES, RGB_HEX_REGEX
 
@@ -338,15 +347,6 @@ def polygons_to_path_patches(element):
         mpl_paths.append(subpath)
     return mpl_paths
 
-try:
-    import cftime
-    from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
-    nc_axis_available = True
-except:
-    from matplotlib.dates import DateConverter
-    NetCDFTimeConverter = DateConverter
-    nc_axis_available = False
-
 
 class CFTimeConverter(NetCDFTimeConverter):
     """

From 5aad6f2023461ba8895c11404962b29abf03d008 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 13:33:17 +0000
Subject: [PATCH 08/14] Various datetime handling fixes

---
 holoviews/core/util.py              | 12 +++---------
 holoviews/plotting/bokeh/element.py |  4 ++--
 holoviews/plotting/bokeh/plot.py    |  2 +-
 holoviews/plotting/bokeh/util.py    |  4 ++--
 holoviews/plotting/mpl/util.py      |  2 +-
 5 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/holoviews/core/util.py b/holoviews/core/util.py
index c5e7d21f60..40883e033b 100644
--- a/holoviews/core/util.py
+++ b/holoviews/core/util.py
@@ -94,13 +94,7 @@ def __cmp__(self, other):
 
 try:
     import cftime
-    cftime_types = (
-        cftime._cftime.DatetimeGregorian,
-        cftime._cftime.Datetime360Day,
-        cftime._cftime.DatetimeJulian,
-        cftime._cftime.DatetimeNoLeap,
-        cftime._cftime.DatetimeProlepticGregorian
-    )
+    cftime_types = (cftime.datetime,)
     datetime_types += cftime_types
 except:
     cftime_types = ()
@@ -1857,7 +1851,7 @@ def cftime_to_timestamp(date, time_unit='us'):
     are converted to standard Gregorian calendar. This can cause
     extra space to be added for dates that don't exist in the original
     calendar. In order to handle these dates correctly a custom bokeh
-    model with support for other calendars would have to be defind.
+    model with support for other calendars would have to be defined.
 
     Args:
         date: cftime datetime object (or array)
@@ -1870,7 +1864,7 @@ def cftime_to_timestamp(date, time_unit='us'):
     if time_unit == 'us':
         tscale = 1
     else:
-        tscale = (np.timedelta64(1, time_unit)/np.timedelta64(1, 'us')) * 1000.
+        tscale = (np.timedelta64(1, 'us')/np.timedelta64(1, time_unit))
     return utime.date2num(date)*tscale
 
 
diff --git a/holoviews/plotting/bokeh/element.py b/holoviews/plotting/bokeh/element.py
index f944c1bd50..f0b3f488c9 100644
--- a/holoviews/plotting/bokeh/element.py
+++ b/holoviews/plotting/bokeh/element.py
@@ -301,7 +301,7 @@ def _axes_props(self, plots, subplots, element, ranges):
                     xtype = el.nodes.get_dimension_type(xdims[0])
                 else:
                     xtype = el.get_dimension_type(xdims[0])
-                if ((xtype is np.object_ and type(l) in util.datetime_types) or
+                if ((xtype is np.object_ and issubclass(type(l), util.datetime_types)) or
                     xtype in util.datetime_types):
                     x_axis_type = 'datetime'
 
@@ -315,7 +315,7 @@ def _axes_props(self, plots, subplots, element, ranges):
                     ytype = el.nodes.get_dimension_type(ydims[0])
                 else:
                     ytype = el.get_dimension_type(ydims[0])
-                if ((ytype is np.object_ and type(b) in util.datetime_types)
+                if ((ytype is np.object_ and issubclass(type(b), util.datetime_types))
                     or ytype in util.datetime_types):
                     y_axis_type = 'datetime'
 
diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index 3eebf86692..1ee2f9c211 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -248,7 +248,7 @@ def _postprocess_data(self, data):
 
             # Certain datetime types need to be converted
             if len(values) and isinstance(values[0], cftime_types):
-                values = cftime_to_timestamp(values)
+                values = cftime_to_timestamp(values, 'ms')
             new_data[k] = values
         return new_data
 
diff --git a/holoviews/plotting/bokeh/util.py b/holoviews/plotting/bokeh/util.py
index 1e1ebbe50a..ca443c0b69 100644
--- a/holoviews/plotting/bokeh/util.py
+++ b/holoviews/plotting/bokeh/util.py
@@ -540,7 +540,7 @@ def date_to_integer(date):
     Attempts highest precision conversion of different datetime
     formats to milliseconds since the epoch (1970-01-01 00:00:00).
     If datetime is a cftime with a non-standard calendar the
-    caveats describd in cftime_to_timestamp apply.
+    caveats described in hv.core.util.cftime_to_timestamp apply.
 
     Args:
         date: Date- or datetime-like object
@@ -557,7 +557,7 @@ def date_to_integer(date):
     if isinstance(date, np.datetime64):
         return time.astype('datetime64[ms]').astype(float)
     elif isinstance(date, cftime_types):
-        return cftime_to_timestamp(date)
+        return cftime_to_timestamp(date, 'ms')
 
     if hasattr(date, 'timetuple'):
         dt_int = calendar.timegm(date.timetuple())*1000
diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index d1a71191d8..da2fd72d0a 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -364,7 +364,7 @@ def convert(cls, value, unit, axis):
         if isinstance(value, cftime_types):
             value = CalendarDateTime(cftime.datetime(*value.timetuple()[0:6]), value.calendar)
         elif isinstance(value, np.ndarray):
-            value = np.array([CalendarDateTime(cftime.datetime(*v.timetuple()[0:6]), v.calendar) for v in value])
+            value = np.array([CalendarDateTime(v.datetime, v.calendar) for v in value])
         return super(CFTimeConverter, cls).convert(value, unit, axis)
 
 

From bef18f65be53b0cc9079bda4e5b9f3100ceb48e7 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 14:10:26 +0000
Subject: [PATCH 09/14] Overhauled datetime handling

---
 holoviews/core/util.py            |  7 +++--
 holoviews/operation/datashader.py | 47 ++++++++++++++++++-------------
 2 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/holoviews/core/util.py b/holoviews/core/util.py
index 40883e033b..4dbdebb377 100644
--- a/holoviews/core/util.py
+++ b/holoviews/core/util.py
@@ -1824,18 +1824,19 @@ def dt_to_int(value, time_unit='us'):
         if time_unit == 'ns':
             tscale = 1
         else:
-            tscale = (np.timedelta64(1, time_unit)/np.timedelta64(1, 'ns')) * 1000.
+            tscale = (np.timedelta64(1, 'ns')/np.timedelta64(1, time_unit))
     elif time_unit == 'ns':
-        tscale = 1000.
+        tscale = 1e9
     else:
         tscale = 1./np.timedelta64(1, time_unit).tolist().total_seconds()
 
     if isinstance(value, np.datetime64):
         value = value.tolist()
+
     if isinstance(value, (int, long)):
         # Handle special case of nanosecond precision which cannot be
         # represented by python datetime
-        return value * 10**-(np.log10(tscale)-3)
+        return value * 10**-(np.log10(tscale))
     try:
         # Handle python3
         return int(value.timestamp() * tscale)
diff --git a/holoviews/operation/datashader.py b/holoviews/operation/datashader.py
index af671ec549..760f0fea44 100644
--- a/holoviews/operation/datashader.py
+++ b/holoviews/operation/datashader.py
@@ -23,7 +23,9 @@
                     CompositeOverlay, Dataset, Overlay)
 from ..core.data import PandasInterface, XArrayInterface
 from ..core.sheetcoords import BoundingBox
-from ..core.util import LooseVersion, get_param_values, basestring, datetime_types, dt_to_int
+from ..core.util import (
+    LooseVersion, basestring, cftime_types, cftime_to_timestamp,
+    datetime_types, dt_to_int, get_param_values)
 from ..element import (Image, Path, Curve, RGB, Graph, TriMesh, QuadMesh, Contours)
 from ..streams import RangeXY, PlotSize
 
@@ -321,11 +323,18 @@ def get_agg_data(cls, obj, category=None):
         if category and df[category].dtype.name != 'category':
             df[category] = df[category].astype('category')
 
-        if any(df[d.name].dtype.kind == 'M' for d in (x, y)):
+        if any(df[d.name].dtype.kind == 'M' or isinstance(df[d.name].values[0], cftime_types)
+               for d in (x, y)):
             df = df.copy()
         for d in (x, y):
-            if df[d.name].dtype.kind == 'M':
-                df[d.name] = df[d.name].astype('datetime64[ns]').astype('int64') * 1000.
+            vals = df[d.name].values
+            if len(vals) and isinstance(vals[0], cftime_types):
+                vals = cftime_to_timestamp(vals, 'ns')
+            elif df[d.name].dtype.kind == 'M':
+                vals = vals.astype('datetime64[ns]')
+            else:
+                continue
+            df[d.name] = vals.astype('int64')
         return x, y, Dataset(df, kdims=kdims, vdims=vdims), glyph
 
 
@@ -344,9 +353,9 @@ def _aggregate_ndoverlay(self, element, agg_fn):
         info = self._get_sampling(element, x, y)
         (x_range, y_range), (xs, ys), (width, height), (xtype, ytype) = info
         if xtype == 'datetime':
-            x_range = tuple((np.array(x_range)/10e5).astype('datetime64[us]'))
+            x_range = tuple((np.array(x_range)/1e3).astype('datetime64[us]'))
         if ytype == 'datetime':
-            y_range = tuple((np.array(y_range)/10e5).astype('datetime64[us]'))
+            y_range = tuple((np.array(y_range)/1e3).astype('datetime64[us]'))
         agg_params = dict({k: v for k, v in dict(self.get_param_values(), **self.p).items()
                            if k in aggregate.params()},
                           x_range=x_range, y_range=y_range)
@@ -433,11 +442,11 @@ def _process(self, element, key=None):
 
         (x0, x1), (y0, y1) = x_range, y_range
         if xtype == 'datetime':
-            x0, x1 = (np.array([x0, x1])/10e5).astype('datetime64[us]')
-            xs = (xs/10e5).astype('datetime64[us]')
+            x0, x1 = (np.array([x0, x1])/1e3).astype('datetime64[us]')
+            xs = (xs/1e3).astype('datetime64[us]')
         if ytype == 'datetime':
-            y0, y1 = (np.array([y0, y1])/10e5).astype('datetime64[us]')
-            ys = (ys/10e5).astype('datetime64[us]')
+            y0, y1 = (np.array([y0, y1])/1e3).astype('datetime64[us]')
+            ys = (ys/1e3).astype('datetime64[us]')
         bounds = (x0, y0, x1, y1)
         params = dict(get_param_values(element), kdims=[x, y],
                       datatype=['xarray'], bounds=bounds)
@@ -483,9 +492,9 @@ def _process(self, element, key=None):
         if 'x_axis' in agg.coords and 'y_axis' in agg.coords:
             agg = agg.rename({'x_axis': x, 'y_axis': y})
         if xtype == 'datetime':
-            agg[x.name] = (agg[x.name]/10e5).astype('datetime64[us]')
+            agg[x.name] = (agg[x.name]/1e3).astype('datetime64[us]')
         if ytype == 'datetime':
-            agg[y.name] = (agg[y.name]/10e5).astype('datetime64[us]')
+            agg[y.name] = (agg[y.name]/1e3).astype('datetime64[us]')
 
         if agg.ndim == 2:
             # Replacing x and y coordinates to avoid numerical precision issues
@@ -606,11 +615,11 @@ def _process(self, element, key=None):
 
         # Compute bounds (converting datetimes)
         if xtype == 'datetime':
-            xstart, xend = (np.array([xstart, xend])/10e5).astype('datetime64[us]')
-            xs = (xs/10e5).astype('datetime64[us]')
+            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])/10e5).astype('datetime64[us]')
-            ys = (ys/10e5).astype('datetime64[us]')
+            ystart, yend = (np.array([ystart, yend])/1e3).astype('datetime64[us]')
+            ys = (ys/1e3).astype('datetime64[us]')
         bbox = BoundingBox(points=[(xstart, ystart), (xend, yend)])
 
         params = dict(bounds=bbox)
@@ -632,9 +641,9 @@ def _process(self, element, key=None):
 
             # Convert datetime coordinates
             if xtype == "datetime":
-                rarray[x.name] = (rarray[x.name]/10e5).astype('datetime64[us]')
+                rarray[x.name] = (rarray[x.name]/1e3).astype('datetime64[us]')
             if ytype == "datetime":
-                rarray[y.name] = (rarray[y.name]/10e5).astype('datetime64[us]')
+                rarray[y.name] = (rarray[y.name]/1e3).astype('datetime64[us]')
             regridded[vd] = rarray
         regridded = xr.Dataset(regridded)
 
@@ -957,7 +966,7 @@ def _process(self, element, key=None):
 
         for d in kdims:
             if array[d.name].dtype.kind == 'M':
-                array[d.name] = array[d.name].astype('datetime64[ns]').astype('int64') * 10e-4
+                array[d.name] = array[d.name].astype('datetime64[us]').astype('int64')
 
         with warnings.catch_warnings():
             warnings.filterwarnings('ignore', r'invalid value encountered in true_divide')

From 5eee4b6e86ef960d4679aa53f5b6dca6d892cb98 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 14:19:11 +0000
Subject: [PATCH 10/14] Added warning about non-standard calendars

---
 holoviews/core/util.py           |  1 +
 holoviews/plotting/bokeh/plot.py | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/holoviews/core/util.py b/holoviews/core/util.py
index 4dbdebb377..ca37a5b05e 100644
--- a/holoviews/core/util.py
+++ b/holoviews/core/util.py
@@ -98,6 +98,7 @@ def __cmp__(self, other):
     datetime_types += cftime_types
 except:
     cftime_types = ()
+_STANDARD_CALENDARS = set(['standard', 'gregorian', 'proleptic_gregorian'])
 
 
 class VersionError(Exception):
diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index 1ee2f9c211..fb33142ebc 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -19,7 +19,8 @@
 from ...core.options import SkipRendering
 from ...core.util import (
     basestring, cftime_to_timestamp, cftime_types, datetime_types,
-    get_method_owner, unique_iterator, wrap_tuple, wrap_tuple_streams)
+    get_method_owner, unique_iterator, wrap_tuple, wrap_tuple_streams,
+    _STANDARD_CALENDARS)
 from ...streams import Stream
 from ..links import Link
 from ..plot import (
@@ -248,6 +249,13 @@ def _postprocess_data(self, data):
 
             # Certain datetime types need to be converted
             if len(values) and isinstance(values[0], cftime_types):
+                if any(v.calendar not in _STANDARD_CALENDARS for v in values):
+                    self.param.warning(
+                        'Converting cftime.datetime from a non-standard '
+                        'calendar (%s) to a standard calendar for plotting. '
+                        'This may lead to subtle errors in formatting '
+                        'dates, for accurate tick formatting switch to '
+                        'the matplotlib backend.' % values[0].calendar)
                 values = cftime_to_timestamp(values, 'ms')
             new_data[k] = values
         return new_data

From 4da46b8285867cdc6d0d26dbc7c4c6e64e1d8377 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 14:24:41 +0000
Subject: [PATCH 11/14] Further fix

---
 holoviews/plotting/mpl/util.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index da2fd72d0a..5b6aa18877 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -362,7 +362,7 @@ def convert(cls, value, unit, axis):
                              'using:\n\tconda install -c conda-forge '
                              'nc_time_axis')
         if isinstance(value, cftime_types):
-            value = CalendarDateTime(cftime.datetime(*value.timetuple()[0:6]), value.calendar)
+            value = CalendarDateTime(v.datetime, value.calendar)
         elif isinstance(value, np.ndarray):
             value = np.array([CalendarDateTime(v.datetime, v.calendar) for v in value])
         return super(CFTimeConverter, cls).convert(value, unit, axis)

From e35461218a07fe5a33c1081bf7b81d7fb626af92 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 14:33:39 +0000
Subject: [PATCH 12/14] Added unit tests for cftime conversions

---
 .../tests/plotting/bokeh/testelementplot.py   | 37 ++++++++++++++++++-
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/holoviews/tests/plotting/bokeh/testelementplot.py b/holoviews/tests/plotting/bokeh/testelementplot.py
index 62112e4bad..ac8bece0fe 100644
--- a/holoviews/tests/plotting/bokeh/testelementplot.py
+++ b/holoviews/tests/plotting/bokeh/testelementplot.py
@@ -10,6 +10,7 @@
 from holoviews.plotting.util import process_cmap
 
 from .testplot import TestBokehPlot, bokeh_renderer
+from ...utils import LoggingComparisonTestCase
 
 try:
     from bokeh.document import Document
@@ -19,7 +20,7 @@
 
 
 
-class TestElementPlot(TestBokehPlot):
+class TestElementPlot(LoggingComparisonTestCase, TestBokehPlot):
 
     def test_element_show_frame_disabled(self):
         curve = Curve(range(10)).opts(plot=dict(show_frame=False))
@@ -287,7 +288,6 @@ def test_categorical_axis_fontsize(self):
         curve = Curve([('A', 1), ('B', 2)]).options(fontsize={'minor_xticks': '6pt', 'xticks': 18})
         plot = bokeh_renderer.get_plot(curve)
         xaxis = plot.handles['xaxis']
-        print(xaxis.properties_with_values())
         self.assertEqual(xaxis.major_label_text_font_size, '6pt')
         self.assertEqual(xaxis.group_text_font_size, {'value': '18pt'})
 
@@ -298,6 +298,39 @@ def test_categorical_axis_fontsize_both(self):
         self.assertEqual(xaxis.major_label_text_font_size, {'value': '18pt'})
         self.assertEqual(xaxis.group_text_font_size, {'value': '18pt'})
 
+    def test_cftime_transform_gregorian_no_warn(self):
+        try:
+            import cftime
+        except:
+            raise SkipTest('Test requires cftime library')
+        gregorian_dates = [cftime.DatetimeGregorian(2000, 2, 28),
+                           cftime.DatetimeGregorian(2000, 3, 1),
+                           cftime.DatetimeGregorian(2000, 3, 2)]
+        curve = Curve((gregorian_dates, [1, 2, 3]))
+        plot = bokeh_renderer.get_plot(curve)
+        xs = plot.handles['cds'].data['x']
+        self.assertEqual(xs.astype('int'),
+                         np.array([951696000000, 951868800000, 951955200000]))
+
+    def test_cftime_transform_noleap_warn(self):
+        try:
+            import cftime
+        except:
+            raise SkipTest('Test requires cftime library')
+        gregorian_dates = [cftime.DatetimeNoLeap(2000, 2, 28),
+                           cftime.DatetimeNoLeap(2000, 3, 1),
+                           cftime.DatetimeNoLeap(2000, 3, 2)]
+        curve = Curve((gregorian_dates, [1, 2, 3]))
+        plot = bokeh_renderer.get_plot(curve)
+        xs = plot.handles['cds'].data['x']
+        self.assertEqual(xs.astype('int'),
+                         np.array([951696000000, 951868800000, 951955200000]))
+        substr = (
+            "Converting cftime.datetime from a non-standard calendar "
+            "(noleap) to a standard calendar for plotting. This may "
+            "lead to subtle errors in formatting dates, for accurate "
+            "tick formatting switch to the matplotlib backend.")
+        self.log_handler.assertEndsWith('WARNING', substr)
 
 
 class TestColorbarPlot(TestBokehPlot):

From 49e3b769c1aea48b57dc56ba02f6af5efed272c5 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 16:34:55 +0000
Subject: [PATCH 13/14] Further fixes for datetime handling

---
 holoviews/core/util.py                     | 23 ++++++------
 holoviews/operation/element.py             |  6 ++--
 holoviews/tests/core/testutils.py          |  6 ++--
 holoviews/tests/operation/testoperation.py | 42 ++++++++++++++--------
 4 files changed, 43 insertions(+), 34 deletions(-)

diff --git a/holoviews/core/util.py b/holoviews/core/util.py
index ca37a5b05e..29573568f4 100644
--- a/holoviews/core/util.py
+++ b/holoviews/core/util.py
@@ -1820,24 +1820,21 @@ def dt_to_int(value, time_unit='us'):
     elif isinstance(value, cftime_types):
         return cftime_to_timestamp(value, time_unit)
 
+    # Handle datetime64 separately
     if isinstance(value, np.datetime64):
-        value = np.datetime64(value, 'ns')
-        if time_unit == 'ns':
-            tscale = 1
-        else:
-            tscale = (np.timedelta64(1, 'ns')/np.timedelta64(1, time_unit))
-    elif time_unit == 'ns':
+        try:
+            value = np.datetime64(value, 'ns')
+            tscale = (np.timedelta64(1, time_unit)/np.timedelta64(1, 'ns'))
+            return value.tolist()/tscale
+        except:
+            # If it can't handle ns precision fall back to datetime
+            value = value.tolist()
+
+    if time_unit == 'ns':
         tscale = 1e9
     else:
         tscale = 1./np.timedelta64(1, time_unit).tolist().total_seconds()
 
-    if isinstance(value, np.datetime64):
-        value = value.tolist()
-
-    if isinstance(value, (int, long)):
-        # Handle special case of nanosecond precision which cannot be
-        # represented by python datetime
-        return value * 10**-(np.log10(tscale))
     try:
         # Handle python3
         return int(value.timestamp() * tscale)
diff --git a/holoviews/operation/element.py b/holoviews/operation/element.py
index 5bb20b10ae..80a9d90685 100644
--- a/holoviews/operation/element.py
+++ b/holoviews/operation/element.py
@@ -589,9 +589,9 @@ def _process(self, element, key=None):
         if data.dtype.kind == 'M' or (data.dtype.kind == 'O' and isinstance(data[0], datetime_types)):
             start, end = dt_to_int(start, 'ns'), dt_to_int(end, 'ns')
             datetimes = True
-            data = data.astype('datetime64[ns]').astype('int64') * 1000.
+            data = data.astype('datetime64[ns]').astype('int64')
             if bins is not None:
-                bins = bins.astype('datetime64[ns]').astype('int64') * 1000.
+                bins = bins.astype('datetime64[ns]').astype('int64')
             else:
                 hist_range = start, end
 
@@ -622,7 +622,7 @@ def _process(self, element, key=None):
             hist = np.zeros(self.p.num_bins)
         hist[np.isnan(hist)] = 0
         if datetimes:
-            edges = (edges/10e5).astype('datetime64[us]')
+            edges = (edges/1e3).astype('datetime64[us]')
 
         params = {}
         if self.p.weight_dimension:
diff --git a/holoviews/tests/core/testutils.py b/holoviews/tests/core/testutils.py
index bd37d5d93f..097a1dceb3 100644
--- a/holoviews/tests/core/testutils.py
+++ b/holoviews/tests/core/testutils.py
@@ -584,15 +584,15 @@ def test_datetime_to_us_int(self):
 
     def test_datetime64_s_to_ns_int(self):
         dt = np.datetime64(datetime.datetime(2017, 1, 1), 's')
-        self.assertEqual(dt_to_int(dt, 'ns'), 1483228800000000000000.0)
+        self.assertEqual(dt_to_int(dt, 'ns'), 1483228800000000000.0)
 
     def test_datetime64_us_to_ns_int(self):
         dt = np.datetime64(datetime.datetime(2017, 1, 1), 'us')
-        self.assertEqual(dt_to_int(dt, 'ns'), 1483228800000000000000.0)
+        self.assertEqual(dt_to_int(dt, 'ns'), 1483228800000000000.0)
 
     def test_datetime64_to_ns_int(self):
         dt = np.datetime64(datetime.datetime(2017, 1, 1))
-        self.assertEqual(dt_to_int(dt, 'ns'), 1483228800000000000000.0)
+        self.assertEqual(dt_to_int(dt, 'ns'), 1483228800000000000.0)
 
     def test_datetime64_us_to_us_int(self):
         dt = np.datetime64(datetime.datetime(2017, 1, 1), 'us')
diff --git a/holoviews/tests/operation/testoperation.py b/holoviews/tests/operation/testoperation.py
index 1f1ed744ca..e76770f5e2 100644
--- a/holoviews/tests/operation/testoperation.py
+++ b/holoviews/tests/operation/testoperation.py
@@ -168,22 +168,30 @@ def test_points_histogram_not_normed(self):
     def test_histogram_operation_datetime(self):
         dates = np.array([dt.datetime(2017, 1, i) for i in range(1, 5)])
         op_hist = histogram(Dataset(dates, 'Date'), num_bins=4)
-        hist_data = {'Date': np.array(['2017-01-01T00:00:00.000000', '2017-01-01T17:59:59.999999',
-                                       '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000',
-                                       '2017-01-04T00:00:00.000000'], dtype='datetime64[us]'),
-                     'Date_frequency': np.array([  3.85802469e-18,   3.85802469e-18,   3.85802469e-18,
-                                                   3.85802469e-18])}
+        hist_data = {
+            'Date': np.array([
+                '2017-01-01T00:00:00.000000', '2017-01-01T18:00:00.000000',
+                '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000',
+                '2017-01-04T00:00:00.000000'], dtype='datetime64[us]'),
+            'Date_frequency': np.array([
+                3.85802469e-18, 3.85802469e-18, 3.85802469e-18,
+                3.85802469e-18])
+        }
         hist = Histogram(hist_data, kdims='Date', vdims=('Date_frequency', 'Frequency'))
         self.assertEqual(op_hist, hist)
 
     def test_histogram_operation_datetime64(self):
         dates = np.array([dt.datetime(2017, 1, i) for i in range(1, 5)]).astype('M')
         op_hist = histogram(Dataset(dates, 'Date'), num_bins=4)
-        hist_data = {'Date': np.array(['2017-01-01T00:00:00.000000', '2017-01-01T17:59:59.999999',
-                                       '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000',
-                                       '2017-01-04T00:00:00.000000'], dtype='datetime64[us]'),
-                     'Date_frequency': np.array([  3.85802469e-18,   3.85802469e-18,   3.85802469e-18,
-                                                   3.85802469e-18])}
+        hist_data = {
+            'Date': np.array([
+                '2017-01-01T00:00:00.000000', '2017-01-01T18:00:00.000000',
+                '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000',
+                '2017-01-04T00:00:00.000000'], dtype='datetime64[us]'),
+            'Date_frequency': np.array([
+                3.85802469e-18, 3.85802469e-18, 3.85802469e-18,
+                3.85802469e-18])
+        }
         hist = Histogram(hist_data, kdims='Date', vdims=('Date_frequency', 'Frequency'))
         self.assertEqual(op_hist, hist)
 
@@ -191,11 +199,15 @@ def test_histogram_operation_datetime64(self):
     def test_histogram_operation_pd_period(self):
         dates = pd.date_range('2017-01-01', '2017-01-04', freq='D').to_period('D')
         op_hist = histogram(Dataset(dates, 'Date'), num_bins=4)
-        hist_data = {'Date': np.array(['2017-01-01T00:00:00.000000', '2017-01-01T17:59:59.999999',
-                                       '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000',
-                                       '2017-01-04T00:00:00.000000'], dtype='datetime64[us]'),
-                     'Date_frequency': np.array([  3.85802469e-18,   3.85802469e-18,   3.85802469e-18,
-                                                   3.85802469e-18])}
+        hist_data = {
+            'Date': np.array([
+                '2017-01-01T00:00:00.000000', '2017-01-01T18:00:00.000000',
+                '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000',
+                '2017-01-04T00:00:00.000000'], dtype='datetime64[us]'),
+            'Date_frequency': np.array([
+                3.85802469e-18, 3.85802469e-18, 3.85802469e-18,
+                3.85802469e-18])
+        }
         hist = Histogram(hist_data, kdims='Date', vdims=('Date_frequency', 'Frequency'))
         self.assertEqual(op_hist, hist)
 

From 23fabdd8c362f2e0207c8f85cc3f0faffa4e6aaa Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Thu, 6 Dec 2018 17:24:06 +0000
Subject: [PATCH 14/14] Fixed flakes

---
 holoviews/plotting/bokeh/plot.py              |  5 ++---
 holoviews/plotting/bokeh/util.py              |  2 +-
 holoviews/plotting/mpl/util.py                |  3 +--
 .../tests/plotting/bokeh/testhistogramplot.py | 20 ++++++++++++-------
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index fb33142ebc..f7c745ee88 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -18,9 +18,8 @@
 )
 from ...core.options import SkipRendering
 from ...core.util import (
-    basestring, cftime_to_timestamp, cftime_types, datetime_types,
-    get_method_owner, unique_iterator, wrap_tuple, wrap_tuple_streams,
-    _STANDARD_CALENDARS)
+    basestring, cftime_to_timestamp, cftime_types, get_method_owner,
+    unique_iterator, wrap_tuple, wrap_tuple_streams, _STANDARD_CALENDARS)
 from ...streams import Stream
 from ..links import Link
 from ..plot import (
diff --git a/holoviews/plotting/bokeh/util.py b/holoviews/plotting/bokeh/util.py
index ca443c0b69..94063666d9 100644
--- a/holoviews/plotting/bokeh/util.py
+++ b/holoviews/plotting/bokeh/util.py
@@ -34,7 +34,7 @@
 from ...core.overlay import Overlay
 from ...core.util import (
     LooseVersion, _getargspec, basestring, callable_name, cftime_types,
-    cftime_to_timestamp, dt64_to_dt, pd, unique_array)
+    cftime_to_timestamp, pd, unique_array)
 from ...core.spaces import get_nested_dmaps, DynamicMap
 from ..util import dim_axis_label
 
diff --git a/holoviews/plotting/mpl/util.py b/holoviews/plotting/mpl/util.py
index 5b6aa18877..701744afa6 100644
--- a/holoviews/plotting/mpl/util.py
+++ b/holoviews/plotting/mpl/util.py
@@ -17,7 +17,6 @@
     validate_joinstyle)
 
 try:
-    import cftime
     from nc_time_axis import NetCDFTimeConverter, CalendarDateTime
     nc_axis_available = True
 except:
@@ -362,7 +361,7 @@ def convert(cls, value, unit, axis):
                              'using:\n\tconda install -c conda-forge '
                              'nc_time_axis')
         if isinstance(value, cftime_types):
-            value = CalendarDateTime(v.datetime, value.calendar)
+            value = CalendarDateTime(value.datetime, value.calendar)
         elif isinstance(value, np.ndarray):
             value = np.array([CalendarDateTime(v.datetime, v.calendar) for v in value])
         return super(CFTimeConverter, cls).convert(value, unit, axis)
diff --git a/holoviews/tests/plotting/bokeh/testhistogramplot.py b/holoviews/tests/plotting/bokeh/testhistogramplot.py
index c1f5a28f64..e405daa790 100644
--- a/holoviews/tests/plotting/bokeh/testhistogramplot.py
+++ b/holoviews/tests/plotting/bokeh/testhistogramplot.py
@@ -59,13 +59,19 @@ def test_histogram_datetime64_plot(self):
         hist = histogram(Dataset(dates, 'Date'), num_bins=4)
         plot = bokeh_renderer.get_plot(hist)
         source = plot.handles['source']
-        data = {'top': np.array([  3.85802469e-18,   3.85802469e-18,   3.85802469e-18, 3.85802469e-18]),
-                'left': np.array(['2017-01-01T00:00:00.000000', '2017-01-01T17:59:59.999999',
-                                  '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000'],
-                                 dtype='datetime64[us]'),
-                'right': np.array(['2017-01-01T17:59:59.999999', '2017-01-02T12:00:00.000000',
-                                   '2017-01-03T06:00:00.000000', '2017-01-04T00:00:00.000000'],
-                                  dtype='datetime64[us]')}
+        print(source.data)
+        data = {
+            'top': np.array([
+                3.85802469e-18, 3.85802469e-18, 3.85802469e-18, 3.85802469e-18]),
+            'left': np.array([
+                '2017-01-01T00:00:00.000000', '2017-01-01T18:00:00.000000',
+                '2017-01-02T12:00:00.000000', '2017-01-03T06:00:00.000000'],
+                dtype='datetime64[us]'),
+            'right': np.array([
+                '2017-01-01T18:00:00.000000', '2017-01-02T12:00:00.000000',
+                '2017-01-03T06:00:00.000000', '2017-01-04T00:00:00.000000'],
+                dtype='datetime64[us]')
+        }
         for k, v in data.items():
             self.assertEqual(source.data[k], v)
         xaxis = plot.handles['xaxis']