Utilize Templates#

Welcome to the world of Panel templates! In this tutorial, we’ll explore how to harness pre-made templates to effortlessly structure your app with a header, sidebar, and main area.

Templates offer a streamlined approach to app layout and design, providing:

  • Ready-made templates accessible in the pn.template namespace.

  • A variety of customizable options to suit your specific needs.

Crafting a Hello World App#

Let’s start by creating a basic app using the FastListTemplate. Copy the following code into a file named app.py:

import panel as pn

pn.extension()

pn.template.FastListTemplate(
    title="Hello World",
    sidebar=["# Hello Sidebar", "This is text for the *sidebar*"],
    main=["# Hello Main", "This is text for the *main* area"],
).servable()

Serve the app with:

panel serve app.py --autoreload

It should resemble the following:

Hello World FastListTemplate App

Note

In the code snippet:

  • pn.template.FastListTemplate defines the template to use.

  • title sets an optional title for the top header.

  • sidebar and main designate content areas for the sidebar and main section, respectively.

For additional configuration options, refer to the FastListTemplate reference guide.

Tip

Panel offers a rich assortment of built-in templates, including a versatile Slides template.

Take a moment to explore the Templates Section in the Component Gallery, then return here.

Integrating Templates in a Notebook#

While templates shine in serving apps, they’re currently not displayable within notebooks. Copy the following two code cells into a notebook:

import panel as pn

pn.extension()

pn.template.FastListTemplate(
    title="Hello World",
    sidebar=["# Hello Sidebar", "This is text for the *sidebar*"],
    main=["# Hello Main", "This is text for the *main* area"],
).servable()

Append a ; after .servable() to prevent template display in the notebook. Preview the app; it should resemble:

Hello World FastListTemplate App

Warning

Notebook display of templates is not currently supported. Show your support for this feature by upvoting Issue #2677.

Tailoring the Template#

Let’s customize the template further. Copy the code below into app.py:

import panel as pn
import pandas as pd
import altair as alt

pn.extension("vega")

ACCENT = "teal"

image = pn.pane.JPG("https://assets.holoviz.org/panel/tutorials/wind_turbines_sunset.png")

if pn.config.theme=="dark":
    alt.themes.enable("dark")
else:
    alt.themes.enable("default")

@pn.cache # Add caching to only download data once
def get_data():
    return pd.read_csv("https://assets.holoviz.org/panel/tutorials/turbines.csv.gz")

df = get_data()

top_manufacturers = (
    df.groupby("t_manu").p_cap.sum().sort_values().iloc[-10:].index.to_list()
)
df = df[df.t_manu.isin(top_manufacturers)]
fig = (
    alt.Chart(
        df.sample(5000),
        title="Capacity by Manufacturer",
    )
    .mark_circle(size=8)
    .encode(
        y="t_manu:N",
        x="p_cap:Q",
        yOffset="jitter:Q",
        color=alt.Color("t_manu:N").legend(None),
        tooltip=["t_manu", "p_cap"],
    )
    .transform_calculate(jitter="sqrt(-2*log(random()))*cos(2*PI*random())")
    .properties(
        height="container",
        width="container",
    )
)
plot = pn.pane.Vega(fig, sizing_mode="stretch_both", max_height=800, margin=20)

pn.template.FastListTemplate(
    title="Wind Turbine Manufacturers",
    sidebar=[image, "**Note**: Only the 10 Manufacturers with the largest installed capacity are shown in the plot."],
    main=["# Installed Capacity", plot],
    accent=ACCENT,
    main_layout=None,
).servable()

Serve the app with:

panel serve app.py --autoreload

It should appear as shown below. Try toggling the theme button in the upper right corner.

Customized FastListTemplate App

Upon toggling, the app should switch to dark mode:

Customized FastListTemplate App

Note

In the code:

  • pn.config.theme determines the selected theme (“default” or “dark”).

  • alt.themes.enable("dark") applies the “dark” theme to the plot. Panel doesn’t do this automatically.

  • accent sets the primary or accent color for the template, allowing quick branding of the app.

  • main_layout specifies a layout to wrap each object in the main list. Choose from "card" (default) or None.

Note that accent and main_layout are exclusive to Fast templates like FastListTemplate and FastGridTemplate.

Recap#

In this tutorial, we’ve explored the power of pre-made templates for structuring your app with ease:

  • Templates are available in the pn.template namespace.

  • Find a variety of templates in the Templates Section of the Component Gallery.

  • Templates offer high customizability.

References#

How-to Guides#

Explanations#