Cookbook

See also

PyWebIO Battery

Interaction related

Equivalent to “Press any key to continue”

actions(buttons=["Continue"])

Output pandas dataframe

import numpy as np
import pandas as pd

df = pd.DataFrame(np.random.randn(6, 4), columns=list("ABCD"))
put_html(df.to_html(border=0))

See also

pandas.DataFrame.to_html — pandas documentation

Output Matplotlib figure

Instead of using matplotlib.pyplot.show(), to show matplotlib figure in PyWebIO, you need to save the figure to in-memory buffer fist and then output the buffer via pywebio.output.put_image():

import matplotlib
import matplotlib.pyplot as plt
import io
import pywebio

matplotlib.use('agg')  # required, use a non-interactive backend

fig, ax = plt.subplots()  # Create a figure containing a single axes.
ax.plot([1, 2, 3, 4], [1, 4, 2, 3])  # Plot some data on the axes.

buf = io.BytesIO()
fig.savefig(buf)
pywebio.output.put_image(buf.getvalue())

The matplotlib.use('agg') is required so that the server does not try to create (and then destroy) GUI windows that will never be seen.

When using Matplotlib in a web server (multiple threads environment), pyplot may cause some conflicts in some cases, read the following articles for more information:

• Multi Threading in Python and Pyplot | by Ranjitha Korrapati | Medium

• Embedding in a web application server (Flask) — Matplotlib documentation

Add new syntax highlight for code output

When output code via put_markdown() or put_code(), PyWebIO provides syntax highlight for some common languages. If you find your code have no syntax highlight, you can add the syntax highlighter by two following steps:

1. Go to prismjs CDN page to get your syntax highlighter link.

2. Use config(js_file=...) to load the syntax highlight module

@config(js_file="https://cdn.jsdelivr.net/npm/prismjs@1.23.0/components/prism-diff.min.js")
def main():
    put_code("""
+ AAA
- BBB
CCC
    """.strip(), language='diff')

    put_markdown("""
    ```diff
    + AAA
    - BBB
    CCC
    ```
    """, lstrip=True)

Web application related

Add Google AdSense/Analytics code

When you setup Google AdSense/Analytics, you will get a javascript file and a piece of code that needs to be inserted into your application page, you can use pywebio.config() to inject js file and code to your PyWebIO application:

from pywebio import start_server, output, config

js_file = "https://www.googletagmanager.com/gtag/js?id=G-xxxxxxx"
js_code = """
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());

gtag('config', 'G-xxxxxxx');
"""

@config(js_file=js_file, js_code=js_code)
def main():
    output.put_text("hello world")

start_server(main, port=8080)

Refresh page on connection lost

Add the following code to the beginning of your PyWebIO application main function:

session.run_js('WebIO._state.CurrentSession.on_session_close(()=>{setTimeout(()=>location.reload(), 4000})')