how to periodically update dash
import time from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor import dash import dash_html_components as html import dash_core_components as dcc import plotly.graph_objs as go import numpy as np # number of seconds between re-calculating the data UPDADE_INTERVAL = 5 def get_new_data(): """Updates the global variable 'data' with new data""" global data data = np.random.normal(size=1000) def get_new_data_every(period=UPDADE_INTERVAL): """Update the data every 'period' seconds""" while True: get_new_data() print("data updated") time.sleep(period) def make_layout(): chart_title = "data updates server-side every {} seconds".format(UPDADE_INTERVAL) return html.Div( dcc.Graph( id='chart', figure={ 'data': [go.Histogram(x=data)], 'layout': {'title': chart_title} } ) ) app = dash.Dash(__name__) # get initial data get_new_data() # we need to set layout to be a function so that for each new page load # the layout is re-created with the current data, otherwise they will see # data that was generated when the Dash app was first initialised app.layout = make_layout # Run the function in another thread executor = ThreadPoolExecutor(max_workers=1) executor.submit(get_new_data_every) if __name__ == '__main__': app.run_server(debug=True)
