README.md

Altair Viewer

This repo is no longer maintained. Since Altair 5.3, the functionality of Altair Viewer is now available in Altair via the vl-convert package. See the docs on how to use the browser renderer to display charts via .show(), and the PR vega/altair#3379 for more details.

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Offline chart viewer for Altair visualizations

This package provides tools for viewing Altair charts without a web connection in arbitrary Python environments. Charts can be displayed either inline in a Jupyter notebook environment, or in a separate browser window for use in any environment.

Installation

Altair Viewer can be installed from the Python Package Index with pip:

$ pip install altair_viewer

Usage: General Environments

Altair viewer provides two top-level functions for displaying charts: display() and show(). Their intended use is slightly different:

import altair_viewer
altair_viewer.display(chart)

display(chart) is meant for use in interactive computing environments where a single Python process is used interactively. It will serve a chart viewer at a localhost URL, and any susequent chart created within the session will appear in the same window. The background server will be terminated when the main Python process terminates, so this is not suitable for standalone scripts.

import altair_viewer
altair_viewer.show(chart)

show(chart) is meant for use once at the end of a Python script. It does the same as display(), but automatically opens a browser window, and adds an input prompt to prevent the script (and the server it creates) from terminating.

Usage: IPython & Jupyter

Within Jupyter notebook, IPython terminal, and related environments that support Mimetype-based display, altair viewer can be used by enabling the altair_viewer renderer:

import altair as alt
alt.renderers.enable('altair_viewer')

This will cause charts at the end of a Jupyter notebook cell to be rendered in a separate browser window, as with the display() and show() methods.

If enabled with inline=True, charts will be rendered inline in the notebook:

import altair as alt
alt.renderers.enable('altair_viewer', inline=True)

To display a single inline chart using Altair viewer in an IPython environment without globally enabling the associated renderer, you can use the display method directly:

import altair_viewer
altair_viewer.display(chart, inline=True)

Note that the display based on altair viewer will only function correctly as long as the kernel that created the charts is running, as it depends on the background server started by the kernel. In particular, this means that if you save a notebook and reopen it later, charts will not display until the associated cells are re-run.