Customizing Renderers#
Renderers in Altair are all based on the mimebundle representation accessed by
the _repr_mimebundle_ method of the top-level Altair objects. When you enable
a renderer, functionally what that does is to define a new kind of mimebundle
output.
The alt.renderers registry allows the user to define and enable new mimetypes
for the chart.
As a simple example, imagine we would like to add a plaintext renderer that
renders a chart description in plain text. We could do it this way:
def plaintext_mimetype(spec):
return {'text/plain': "description: " + spec.get('description', 'none')}
alt.renderers.register('plaintext', plaintext_mimetype)
Now you can enable this mimetype, and then when your chart is displayed you will see this description:
alt.renderers.enable('plaintext')
alt.Chart('data.txt').mark_point().encode(
x='x:Q',
y='y:Q'
).properties(
description='This is a simple chart'
)
description: This is a simple chart
This is a simple example, but it shows you the flexibility of this approach.
If you have a frontend that recognizes _repr_mimebundle_ as a means of
obtaining a MIME type representation of a Python object, then you can define
a function that will process the chart content in any way before returning
any mimetype.
The renderers built-in to Altair are the following:
"default": default rendering, using the'application/vnd.vegalite.v2+json'MIME type which is supported by JupyterLab and nteract."html": identical to"default""mimetype": outputs a vega-lite specific mimetype together with a PNG representation."jupyterlab": identical to"mimetype""nteract": identical to"mimetype""colab": renderer for Google’s Colab notebook, using the"text/html"MIME type."notebook": renderer for the classic notebook, provided by the ipyvega package"json": renderer that outputs the raw JSON chart specification, using the'application/json'MIME type."png": renderer that renders and converts the chart to PNG, outputting it using the'image/png'MIME type."svg": renderer that renders and converts the chart to an SVG image, outputting it using the'image/svg+xml'MIME type.