Defer data load¶
Download this notebook from GitHub (right-click to download).
import panel as pn
import pandas as pd
import hvplot.pandas
import time
pn.extension(sizing_mode="stretch_width")
Defer loading of the data and populating the widgets until the page is rendered:
stocks_url = 'https://raw.githubusercontent.com/vega/datalib/master/test/data/stocks.csv'
select_ticker = pn.widgets.Select(name='Stock Ticker', width=250, sizing_mode="fixed")
def load_data():
if 'stocks' not in pn.state.cache:
pn.state.cache['stocks'] = df = pd.read_csv(stocks_url, parse_dates=['date']).set_index('symbol')
else:
df = pn.state.cache['stocks']
symbols = list(df.index.unique())
select_ticker.options = symbols
select_ticker.value = symbols[0]
pn.state.onload(load_data)
If 'stocks' is not yet in cache we show a spinner widget, otherwise let us plot the data:
@pn.depends(select_ticker)
def plot_ticker(ticker):
if 'stocks' not in pn.state.cache or not ticker:
return pn.indicators.LoadingSpinner(value=True)
time.sleep(0.5)
return pn.state.cache['stocks'].loc[ticker].hvplot.line('date', 'price', color="#C01754", line_width=6)
pn.Row(select_ticker, plot_ticker)
App¶
Lets wrap it into nice template that can be served via panel serve defer_data_load.ipynb
pn.template.FastListTemplate(
site="Panel",
title="Defer Data Load",
sidebar=[select_ticker],
main=[
"This app demonstrates how to **defer the loading** of the data and population of the widgets until the page is rendered",
plot_ticker,
]
).servable();
This web page was generated from a Jupyter notebook and not all interactivity will work on this website. Right click to download and run locally for full Python-backed interactivity.
Download this notebook from GitHub (right-click to download).