Updating plot data with periodic callback

Panel
2

Hi

Just given you some idea here:

import pandas as pd
import numpy as np
import random
import panel as pn
import datetime as dt
import holoviews as hv
import time
from holoviews.streams import Pipe
hv.extension('bokeh')
pn.extension()


latest_update = pn.widgets.StaticText()

# define a pip funtionn for streams the data
pipe = Pipe(data=[])
dmap = hv.DynamicMap(hv.Bars, streams=[pipe])

# init the data 
x,y = [x for x in range(10)],[random.randint(0,100) for y in range(10)]
pipe.send((x,y)) 

# define the update funtion
def update_plot():
    latest_update.value = f'updating: {dt.datetime.now().strftime("%c")}'
    time.sleep(0.5)
    x,y = [x for x in range(10)],[random.randint(0,100) for y in range(10)]
    pipe.send((x,y)) 
    latest_update.value = f'latest: {dt.datetime.now().strftime("%c")}'
# period call back
cb = pn.state.add_periodic_callback(update_plot, period=2000, start=False)    

# define the start and stop button
button = pn.widgets.Button(name = 'Click to Start', button_type = 'success')
def button_click(event):
    if button.name == 'Click to Start':
        print('started')
        cb.start()
        button.name = 'started'
        button.button_type = 'danger'
    else:
        print('stoped')
        cb.stop()
        button.name ='Click to Start'
        button.button_type = 'success'
button.on_click(button_click)

# layout
pn.Column(
    button,
    pn.Column(
        dmap
    ),
    latest_update
)

Here is some link learn about stream data:Working with Streaming Data — HoloViews v1.15.3

Kind regards
Victor

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