bokeh callbacks

callbacks.py

from bokeh.models import CustomJS, ColumnDataSource

source = ColumnDataSource(data=dict(x=[0,0], y=[0, 80]))

# Javascript
callback = CustomJS(args=dict(source=source), code="""
        var data = source.data;
        var f = cb_obj.value
        data['x'] = [f, f]

        source.change.emit();
    """)
    
model_obj.js_on_change('value', callback)

# Python

def callback(attrname, old, new):
    source.data['x'] = [new, new]
    
model_obj.on_change('value', callback)