pydata2015 berlin bokeh random walk

code

original

 import collections
 import datetime
 import time

 import numpy as np

 from bokeh.plotting import cursession, figure, show, output_notebook
 # To run these examples you must execute the command
 # python bokeh-server in the top-level Bokeh source directory first.

 output_notebook(url="default")

 TS_MULT_us = 1e6
 UNIX_EPOCH = datetime.datetime(1970, 1, 1, 0, 0) #offset-naive datetime

 def int2dt(ts, ts_mult=TS_MULT_us):
     """Convert timestamp (integer) to datetime"""
     return(datetime.datetime.utcfromtimestamp(float(ts)/ts_mult))
                
 def td2int(td, ts_mult=TS_MULT_us):
     """Convert timedelta to integer"""
     return(int(td.total_seconds()*ts_mult))
                
 def dt2int(dt, ts_mult=TS_MULT_us):
     """Convert datetime to integer"""
     delta = dt - UNIX_EPOCH
     return(int(delta.total_seconds()*ts_mult))
                
 def int_from_last_sample(dt, td):
     return(dt2int(dt) - dt2int(dt) % td2int(td))

 TS_MULT = 1e3
 td_delay = datetime.timedelta(seconds=0.5)
 delay_s = td_delay.total_seconds()
 delay_int = td2int(td_delay, TS_MULT)

 value = 1000 # initial value
 N = 100 # number of elements into circular buffer

 buff = collections.deque([value]*N, maxlen=N)

 t_now = datetime.datetime.utcnow()
 ts_now = dt2int(t_now, TS_MULT)
 t = collections.deque(np.arange(ts_now-N*delay_int, ts_now, delay_int), maxlen=N)

 p = figure(x_axis_type="datetime")
 p.line(list(t), list(buff), color="#0000FF", name="line_example")

 renderer = p.select(dict(name="line_example"))[0]
 ds = renderer.data_source
 show(p)
 while True:
     ts_now = dt2int(datetime.datetime.utcnow(), 1e3)
     t.append(ts_now)
     ds.data['x'] = list(t)

     value += np.random.uniform(-1, 1)
     buff.append(value)
     ds.data['y'] = list(buff)
            
     cursession().store_objects(ds)
     time.sleep(delay_s)

convert to bokeh 0.11

 #! coding: utf-8

 import collections
 import datetime
 import time

 import numpy as np

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


 # *To run these examples you must execute the command
 # `bokeh serve` in the top-level Bokeh source directory first.*

 TS_MULT_us = 1e6
 # offset-naive datetime
 UNIX_EPOCH = datetime.datetime(1970, 1, 1, 0, 0)


 def int2dt(ts, ts_mult=TS_MULT_us):
     """Convert timestamp (integer) to datetime"""
     return(datetime.datetime.utcfromtimestamp(float(ts)/ts_mult))


 def td2int(td, ts_mult=TS_MULT_us):
     """Convert timedelta to integer"""
     return(int(td.total_seconds()*ts_mult))


 def dt2int(dt, ts_mult=TS_MULT_us):
     """Convert datetime to integer"""
     delta = dt - UNIX_EPOCH
     return(int(delta.total_seconds()*ts_mult))


 def int_from_last_sample(dt, td):
     return(dt2int(dt) - dt2int(dt) % td2int(td))


 TS_MULT = 1e3
 td_delay = datetime.timedelta(seconds=0.5)
 delay_s = td_delay.total_seconds()
 delay_int = td2int(td_delay, TS_MULT)

 # initial value
 value = 1000
 # number of elements into circular buffer
 N = 100

 buff = collections.deque([value]*N, maxlen=N)


 t_now = datetime.datetime.utcnow()
 ts_now = dt2int(t_now, TS_MULT)
 t = collections.deque(np.arange(ts_now-N*delay_int, ts_now, delay_int), maxlen=N)

 p = figure(x_axis_type="datetime")
 p.line(list(t), list(buff), color="#0000FF", name="line_example")

 renderer = p.select(dict(name="line_example"))[0]
 ds = renderer.data_source


 def update():
     ts_now = dt2int(datetime.datetime.utcnow(), 1e3)
     t.append(ts_now)
     ds.data['x'] = list(t)

     global value
     value += np.random.uniform(-1, 1)
     buff.append(value)
     ds.data['y'] = list(buff)

 # run every 50 milliseconds
 curdoc().add_periodic_callback(update, delay_s * 100)

 session = push_session(curdoc())
 # open the doc in browser
 session.show()

 # run forever
 session.loop_until_closed()

curdoc()

bokeh.io.curdoc
description
1. return the document for the current default state

add_periodic_callback(callback, period_milliseconds)

bokeh.document.Document.add_periodic_callback
description
1. add a callback to be invoked on a session periodic

parameters

callback callable the callback function to execute

period_milliseconds int the number of milliseconds that should be between each callback execution

 note:
 periodic callbacks only work within the context of a bokeh server session
 this function will no effect when bokeh outputs to standalone html or jupyter notebook cells

push_session(document, session_id=None, url=’default’, app_path=’/’, io_loop=None)

bokeh.client.session.push_session
description
1. create a session by pushing the given document to the server
2. overwriting any existing server side document
3. session.document in the returned session will be your supplied document
```
 while the connection to the server if open
 changes make on server side will be applied to this document
 changes made on client side will be synced to the server
```
parameters
1. document bokeh.document.Document the document to be pushed and set as session.document
2. session_id str, optional the name of the session, None to autogenerate a random one (default: None)
3. url str, optional the base server url to connect to (default: None)
4. app_path str, optional relative path to the app on the server (default: ‘/’)
5. io_loop tornado.ioloop.IOLoop, optional the IOLoop to used for the websocket