Dynamic * doesn't work in open stream mode

[jlstevens]

The following doesn't work as expected:

import holoviews as hv
import param
from holoviews import streams
import numpy as np
hv.notebook_extension()

class Time(streams.Stream):
    time = param.Number(default=1)
    
time_stream = Time()
tdim = 'time'
dmap1 = hv.DynamicMap(lambda time: hv.Image(np.random.rand(10,10)*time), kdims=[tdim], streams=[time_stream])
dmap2 = hv.DynamicMap(lambda time: hv.Image(-np.random.rand(10,10)*time), kdims=[tdim], streams=[time_stream])
dmap1 * dmap2

I get:

/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/mpl/raster.pyc in update_handles(self, key, axis, element, ranges, style)
     79     def update_handles(self, key, axis, element, ranges, style):
     80         im = self.handles['artist']
---> 81         data, style, axis_kwargs = self.get_data(element, ranges, style)
     82         l, r, b, t = style['extent']
     83         im.set_data(data[0])

/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/mpl/raster.pyc in get_data(self, element, ranges, style)
     65         else:
---> 66             l, b, r, t = element.extents
     67         if self.invert_yaxis and type(element) is Raster:
     68             b, t = t, b

ValueError: need more than 0 values to unpack

This suggests that element is an Overlay so element.extents is creating a new overlay. But if I give the time dimension a range:

tdim = hv.Dimension('time', range=(1,100))

It now works as expected. Setting the range shouldn't be necessary to make dynamic overlays work in open mode...

[jlstevens]

I encountered another confusing issue. In the example above, if you try to use the opts magic as follows:

%%opts Image {+axiswise}

I get a traceback ending in:

/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/plot.pyc in _get_frame(self, key)
    614         elif self.dynamic:
    615             with dimensionless_cache(self.hmap, not self._force or not self.drawn):
--> 616                 key, frame = util.get_dynamic_item(self.hmap, self.dimensions, key)
    617             traverse_setter(self, '_force', False)
    618             if not isinstance(key, tuple): key = (key,)

/Users/jstevens/Desktop/development/holoviews/holoviews/core/util.pyc in get_dynamic_item(map_obj, dimensions, key)
    972         el = map_obj.map(lambda x: x[key], ['DynamicMap'])
    973     elif key >= map_obj.counter:
--> 974         el = next(map_obj)
    975         key = list(map_obj.keys())[-1]
    976     else:

/Users/jstevens/Desktop/development/holoviews/holoviews/core/spaces.py in next(self)
    778         """
    779         if self.mode == 'bounded':
--> 780             raise Exception("The next() method should only be called in "
    781                             "one of the open modes.")
    782 

Exception: The next() method should only be called in one of the open modes.

This time this only happens when the range is specified on the time dimension!

[jlstevens]

When I use the cell magic (%%opts Image {+axiswise}) and hv.Dimension('time', range=(1,100)), I notice that get_dynamic_item gets the non-tuple key 1.

[philippjfr]

There is no more open stream mode, closing.