Build Streaming Dashboard

In this tutorial, we come together to create a simple streaming dashboard to monitor the wind speed and power output of one of our wind turbines:

• We will use pn.state.add_periodic_callback to trigger a task to run on a schedule.

Note

When we ask to run the code in the sections below, you may either execute the code directly in the Panel docs via the green run button, in a cell in a notebook, or in a file app.py that is served with panel serve app.py --dev.

Install the Dependencies

Please ensure that SciPy is installed.

conda

conda install -y -c conda-forge panel scipy

pip

pip install panel scipy

Build the App

Run the code below:

import numpy as np
import panel as pn
from scipy.interpolate import interp1d

pn.extension()

WIND_SPEEDS = np.array([0, 3, 6, 9, 12, 15, 18, 21])  # Wind speed (m/s)
WIND_SPEED_MEAN = 8
WIND_SPEED_STD_DEV = 0.5
POWER_OUTPUTS = np.array([0, 0.03, 0.20, 0.6, 1.0, 1.0, 0, 0])  # Power output (MW)

# Define State

wind_speed = pn.rx(8.0)

## Extract Data

def get_wind_speed():
    # Replace with your own wind speed source
    return round(
        np.random.normal(WIND_SPEED_MEAN, WIND_SPEED_STD_DEV), 1
    )

## Transform Data

power_interpolation = interp1d(
    WIND_SPEEDS, POWER_OUTPUTS, kind="linear", fill_value="extrapolate"
)

def get_power_output(wind_speed):
    return np.round(power_interpolation(wind_speed), 2)

## View Data

wind_speed_view = pn.indicators.Number(
    name="Wind Speed",
    value=wind_speed,
    format="{value} m/s",
    colors=[(10, "green"), (100, "red")],
)
power_output_view = pn.indicators.Number(
    name="Power Output",
    value=wind_speed.rx.pipe(get_power_output),
    format="{value} MW",
    colors=[(10, "green"), (100, "red")],
)

# Update data periodically

def update_wind_speed():
    wind_speed.rx.value = get_wind_speed()

pn.state.add_periodic_callback(update_wind_speed, period=1000)

# Layout the app

pn.Column(
    "# WTG Monitoring Dashboard",
    pn.FlexBox(wind_speed_view, power_output_view),
).servable()

Try changing the period from 1000 to 100.

Note

The code refers to

• wind_speed = pn.rx(8.0): This is a reactive expression with an initial value of 8.0. The UI updates whenever the value wind_speed.rx.value is changed.

• pn.state.add_periodic_callback(update_wind_speed, period=1000): This updates the wind_speed_rx.value every 1000 milliseconds.

Resources

How-to

• Periodically Run Callbacks

App Gallery

• Streaming VideoStream