GitHub Repository: holoviz/panel
Path: blob/main/doc/tutorials/basic/templates.md
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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 --dev

It should resemble the following:

:::{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:

:::{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.theme.enable("dark")
else:
    alt.theme.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 --dev

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

Upon toggling, the app should switch to dark mode:

:::{note} In the code:

pn.config.theme determines the selected theme ("default" or "dark").
alt.theme.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

Templates Overview

Component Gallery

Explore the Templates Section in the Component Gallery for more options.