Provides API for loading themes


Provide a Theme class for specifying new default values for Bokeh Model properties.

class Theme(filename=None, json=None)[source]

Provide new default values for Bokeh models.

Bokeh Model properties all have some built-in default value. If a property has not been explicitly set (e.g. = 10) then accessing the property with return the default value. It may be useful for users to be able to specify a different set of default values than the built-in default. The Theme class allows collections of custom default values to be easily applied to Bokeh documents.

The Theme class can be constructed either from a YAML file or from a JSON dict (but not both). The data should have a top level attrs key, followed by

Examples of both formats are shown below.

  • filename (str, optional) – path to a YAML theme file
  • json (str, optional) – a JSON dictionary specifying theme values

ValueError – If neither filename or json is supplied.


Themes are specified by providing a top-level key attrs which has blocks for Model types to be themed. Each block has keys and values that specify the new property defaults for that type.

Here is an example theme in YAML format that sets various visual properties for all figures, grids, and titles:

        background_fill_color: '#2F2F2F'
        border_fill_color: '#2F2F2F'
        outline_line_color: '#444444'
        grid_line_dash: [6, 4]
        grid_line_alpha: .3
        text_color: "white"

Here is the same theme, in JSON format:

'attrs' : {
    'Figure' : {
        'background_fill_color': '#2F2F2F',
        'border_fill_color': '#2F2F2F',
        'outline_line_color': '#444444',
    'Grid': {
        'grid_line_dash': [6, 4]',
        'grid_line_alpha': .3,
    'Title': {
        'text_color': 'white'

Apply this theme to a model.


Typically, don’t call this method directly. Instead, set the theme on the Document the model is a part of.