atkat12 atkat12 - 3 months ago 26
Python Question

iPyWidget with date slider?

I am wondering if there's an easy way to build an iPyWidget with a datetime slider. Right now it is easy to slide over integer or floating point ranges (e.g. numbers 1-10, decimals 0.01, 0.02, ...).

I imagine you could convert dates to floats or integers, build some sort of slider using these, and then convert back to dates for the display labels on the slider. However, this seems clunky. Does anyone have a smoother solution?

Answer

I had the same issue recently. I had to write my own class to do a daterange picker. Here is my code:

import pandas as pd
import ipywidgets as widgets
from IPython.display import display

class DateRangePicker(object):
    def __init__(self,start='2015-05-02',end="2016-06-02",freq='D',fmt='%Y-%m-%d'):
        """
        Parameters
        ----------
        date_range : pandas.DatetimeIndex
        """
        self.date_range=pd.date_range(start=start,end=end,freq=freq)
        options = [(item.strftime(fmt),item) for item in self.date_range]
        self.slider_start = widgets.SelectionSlider(
            description='start',
            options=options,
            continuous_update=False
        )
        self.slider_end = widgets.SelectionSlider(
            description='end',
            options=options,
            continuous_update=False,
            value=options[-1][1]
        )

        self.slider_start.on_trait_change(self.slider_start_changed, 'value')
        self.slider_end.on_trait_change(self.slider_end_changed, 'value')

        self.widget = widgets.Box(children=[self.slider_start,self.slider_end])

    def slider_start_changed(self,key,value):
        self.slider_end.value=max(self.slider_start.value,self.slider_end.value)
        self._observe(start=self.slider_start.value,end=self.slider_end.value)

    def slider_end_changed(self,key,value):
        self.slider_start.value=min(self.slider_start.value,self.slider_end.value)
        self._observe(start=self.slider_start.value,end=self.slider_end.value)

    def display(self):
        display(self.slider_start,self.slider_end)

    def _observe(self,**kwargs):
        if hasattr(self,'observe'):
            self.observe(**kwargs)

def fct(start,end):
    print start,end

Using it is relatively straightforward:

w=DateRangePicker(start='2016-08-02',end="2016-09-02",freq='D',fmt='%Y-%m-%d')
w.observe=fct
w.display()

Enjoy ;-)