I tried to use FloatRangeSlider from ipywidgets in a jupyter-notebook such that the date is displayed:
import ipywidgets as widgets
from datetime import datetime
class myd:
    def __init__(self, value_datetime):
        self.value = value_datetime
    def __float__(self):
        return float(self.value.strftime("%s"))
    def __format__(self, format_spec):
        return self.value.strftime("%d.%m.%Y")
# Test
start = myd(datetime(2017,1,1))
end = myd(datetime(2017,10,1))
print(float(start), "{:.1f}".format(start))
print(float(end), "{:.1f}".format(end))
which correctly prints
1483225200.0 01.01.2017
1506808800.0 01.10.2017
However, the slider doesn't display as supposed:
widgets.FloatRangeSlider(
    value=[start, end],
    min=start,
    max=end,
    step=100,
    description='Test:',
    disabled=False,
    continuous_update=False,
    orientation='horizontal',
    readout=True,
    readout_format='.1f',
)
It displays
but should display 01.01.2017 - 01.10.2017.
Thanks for any help.
