An example Panel app which changes histograms based on date input.

histogram.py

import random
import datetime as dt
import pandas as pd
import panel as pn

# generate sample data
start = dt.date(2020, 1, 26)
dates = [start + dt.timedelta(days=i) for i in range(10)]
rand = [random.sample(range(0, 100), 50) for i in range(10)]
df = pd.DataFrame(rand, index=dates)

# define widget
date_picker = pn.widgets.DatePicker(name='Date Picker',
                                    start=dates[0], 
                                    end=dates[-1], 
                                    value=dates[0]
                                   )

# bins for histogram
bins = [i for i in range(0, 110, 10)]
hist = df.loc[dates[0]].hist(bins=bins)

# create function
@pn.depends(date_picker.param.value)
def hourly_plot(date=date_picker.param.value, bins=bins, hist=hist):
    hist.figure.clear()
    hist = df.loc[date].hist(bins=bins)
    return hist.figure

# define panel
hourly  = pn.Row(
    pn.Column(date_picker),    
    hourly_plot
)

hourly.servable()