set title of a python `bokeh` plot figure from outside of the `figure()` function

To simply change the title without constructing a new Title object, you can set the figure's title.text attribute:

from bokeh.plotting import figure
p = figure()
p.title.text = 'New title'

Edit: Note that the solution in this answer will not work in bokeh server due to a known bug. This answer below will work and is more pythonic.

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You have to assign an instance of Title to p.title. Since, we are able to investigate the types of things in python using the function type, it is fairly simple to figure out these sorts of things.

> type(p.title) 
bokeh.models.annotations.Title

Here's a complete example in a jupyter notebook:

from bokeh.models.annotations import Title
from bokeh.plotting import figure, show
import numpy as np
from bokeh.io import output_notebook
output_notebook()
x = np.arange(0, 2*np.pi, np.pi/100)
y = np.sin(x)
p = figure()
p.circle(x, y)
t = Title()
t.text = 'new title'
p.title = t
show(p)

outputs the following chart with the title set to new title: