How to animate a circle using bokeh

Question

Note from maintainers: This question concerns the obsolete first generation Bokeh server. For details about modern Bokeh server applications, see:

https://docs.bokeh.org/en/latest/docs/user_guide/server.html

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OBSOLETE:

I am currently working on this simple project using bokeh plotting through a server, attempting to move a circle in a circle. The two examples that I have been trying to learn from are https://github.com/bokeh/bokeh/blob/master/examples/plotting/server/animated.py and https://github.com/bokeh/bokeh/blob/master/examples/plotting/server/line_animate.py

As their documentation is still very limited, if anyone could help, that would be great.

import time 
import numpy as np
from bokeh.plotting import cursession, figure, show, output_server


output_server("circle_server")

pl = figure(y_range=(-2,2), x_range=(-2,2))

x=1
y=0

pl.circle(x, y, size=25, alpha=0.6, name="moving_circle") 
pl.annulus(x=0,y=0, inner_radius = 1, outer_radius = 1, line_alpha=0.6)


show(pl)

renderer = pl.select(dict(name="moving_circle"))
ds = renderer[0].data_source



while True:
    for rad in np.linspace(0,2*np.pi,100):
        #rad = deg*np.pi/180
        ds.data["x"] = np.cos(rad)
        ds.data["y"] = np.sin(rad)
        cursession().store_objects(ds)
        time.sleep(0.1)

Answer 1

Note from maintainers: This question concerns the obsolete first generation Bokeh server. For details about modern Bokeh server applications, see:

https://docs.bokeh.org/en/latest/docs/user_guide/server.html

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OBSOLETE:

From the docs here:

http://docs.bokeh.org/en/latest/docs/reference/plotting.html#bokeh.plotting.Figure.circle

circle(plot, *args, **kwargs) - Parameters:

• x (str or list[float]) – values or field names of center x coordinates

• y (str or list[float]) – values or field names of center y coordinates

So, you need to pass your values in a list. To fix it you can just add brackets in [x], [y], [np.cos(rad)] and [np.sin(rad)].

Here's a tested working solution:

import time 
import numpy as np
from bokeh.plotting import cursession, figure, show, output_server


output_server("circle_server")

pl = figure(y_range=(-2,2), x_range=(-2,2))

x=1
y=0


pl.circle(x=[x], y=[y], size=25, alpha=0.6, name="circle") 
pl.annulus(x=0,y=0, inner_radius = 1, outer_radius = 1, line_alpha=0.6)


show(pl)

renderer = pl.select(dict(name="circle"))

ds = renderer[0].data_source

while True:
    for rad in np.linspace(0,2*np.pi,100):
        #rad = deg*np.pi/180
        ds.data["x"] = [np.cos(rad)]
        ds.data["y"] = [np.sin(rad)]
        cursession().store_objects(ds)
        time.sleep(0.5)

Answer 2

Note from maintainers: This question concerns the obsolete first generation Bokeh server. For details about modern Bokeh server applications, see:

https://docs.bokeh.org/en/latest/docs/user_guide/server.html

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OBSOLETE:

For future reference cursession is outdated and one should migrate to bokeh.session as discussed here.

An (annular wedge) example with animation can be found here.

# You must first run "bokeh serve" to view this example

from numpy import pi, cos, sin, linspace, roll

from bokeh.client import push_session
from bokeh.io import curdoc
from bokeh.plotting import figure

M = 5
N = M*10 + 1
r_base = 8
theta = linspace(0, 2*pi, N)
r_x = linspace(0, 6*pi, N-1)
rmin = r_base - cos(r_x) - 1
rmax = r_base + sin(r_x) + 1

colors = ["FFFFCC", "#C7E9B4", "#7FCDBB", "#41B6C4", "#2C7FB8", "#253494", "#2C7FB8", "#41B6C4", "#7FCDBB", "#C7E9B4"] * M

# figure() function auto-adds the figure to curdoc()
p = figure(x_range=(-11, 11), y_range=(-11, 11))
r = p.annular_wedge(0, 0, rmin, rmax, theta[:-1], theta[1:],
                fill_color=colors, line_color="white")

# open a session to keep our local document in sync with server
session = push_session(curdoc())

ds = r.data_source

def update():
    rmin = roll(ds.data["inner_radius"], 1)
    rmax = roll(ds.data["outer_radius"], -1)
    ds.data.update(inner_radius=rmin, outer_radius=rmax)

curdoc().add_periodic_callback(update, 30)

session.show(p) # open the document in a browser

session.loop_until_closed() # run forever