InteractiveImage with datashader

Hi,
I’m experimenting with manipulating datashader plots in bokeh and would like to do so within server apps. I think this is still bokeh question anyway.

My starting point is to adapt the NYC taxi notebook to minimal code (below). The issue is that the resulting server plot does not resample as I operate the wheel zoom, while it does resample when InteractiveImage is run within the jupyter notebook (and it’s awesome when it does). This makes me think I have not set up the document properly (curdoc) or that I’m not properly using the callback. The object help for datashader.bokeh_ext (Also below) indicates that this is possible (“could be extended to use Bokeh server in that case”) but I can’t tell how.

Any advice?

Apart from InteractiveImage, is there another way to obtain a dynamically updating datashader plot in a boker server app?

Many thanks,

JT

import pandas as pd

from bokeh.plotting import figure, output_notebook, show

import datashader as ds

from datashader import transfer_functions as tf

from datashader.colors import colormap_select, Hot

from bokeh.io import curdoc

from functools import partial

from datashader.bokeh_ext import InteractiveImage

from IPython.core.display import HTML, display

read in the Taxi dataset

df = pd.read_csv(‘data/nyc_taxi.csv’,usecols= \

     ['pickup_x', 'pickup_y', 'dropoff_x','dropoff_y', 'passenger_count','tpep_pickup_datetime'])

NYC = x_range, y_range = ((-8242000,-8210000), (4965000,4990000))

p = figure(tools=‘pan,wheel_zoom,reset’, plot_width=1000, plot_height=1000,

 x_range=x_range, y_range=y_range, outline_line_color=None,

 min_border=0, min_border_left=0, min_border_right=0,

 min_border_top=0, min_border_bottom=0) 

def create_image(x_range, y_range, w=800, h=800):

cvs = ds.Canvas(plot_width=w, plot_height=h, x_range=x_range, y_range=y_range)

agg = cvs.points(df, 'dropoff_x', 'dropoff_y',  ds.count('passenger_count'))

img = tf.shade(agg, cmap=Hot, how='eq_hist')

return tf.dynspread(img, threshold=0.5, max_px=4)

im = InteractiveImage(p, create_image)

curdoc().add_root§

Help on class InteractiveImage in module datashader.bokeh_ext:

class InteractiveImage(builtin.object)

···

Bokeh-based interactive image object that updates on pan/zoom

events.

Given a Bokeh plot and a callback function, calls the function

whenever the pan or zoom changes the plot’s extent, regenerating

the image dynamically. Works in a Jupyter/IPython notebook cell,

using the existing notebook kernel Python process (not a separate

Bokeh server). Does not yet support usage outside the notebook,

but could be extened to use Bokeh server in that case.

Hi,
I’m experimenting with manipulating datashader plots in bokeh and would
like to do so within server apps. I think this is still bokeh question
anyway.

My starting point is to adapt the NYC taxi notebook to minimal code
(below). The issue is that the resulting server plot does not resample as I
operate the wheel zoom, while it *does* resample when InteractiveImage is
run within the jupyter notebook (and it’s awesome when it does). This makes
me think I have not set up the document properly (curdoc) or that I’m not
properly using the callback. The object help for datashader.bokeh_ext (Also
below) indicates that this is possible (“could be extended to use Bokeh
server in that case”) but I can’t tell how.

Any advice?

As described in https://github.com/bokeh/datashader/issues/147 , we have
not yet had the manpower to develop a Bokeh-server equivalent to
InteractiveImage, and probably won't do so any time soon. The dashboard
example included with datashader shows one way to get similar functionality
outside of the notebook, but it is not a simple drop-in replacement for
InteractiveImage, so it will take a bit of work to adapt that approach to
your particular application.

Apart from InteractiveImage, is there another way to obtain a dynamically

updating datashader plot in a boker server app?

Yes! Almost! We've added datashader support to HoloViews (in the upcoming
1.7 release, or in github master), which covers InteractiveImage's
functionality (and much more), and in some cases it supports Bokeh Server.
Unfortunately, there's still a to-do list (at
https://github.com/ioam/holoviews/pull/959) before this functionality can
be merged into master, so there is not currently any Bokeh Server support
available for users just yet. Soon, I hope!

Jim

···

On Wed, Jan 11, 2017 at 3:52 PM, Jason Tumlinson <[email protected]> wrote: