Bokeh python callback to print new attribute value

Question

I am trying to get the data for lasso selected points on a Bokeh scatter chart using a callback.

I am working off an example shown here: Bokeh Server callback from tools

from bokeh.plotting import figure, curdoc, show, output_file
from bokeh.models import ColumnDataSource
from bokeh.layouts import column
from bokeh.io import curdoc
import pandas as pd
import numpy as np

df = pd.DataFrame(np.random.randint(0,100,size=(100, 2)), columns=list('XY'))

source=ColumnDataSource(df)

p = figure(title="Some Figure", tools=["lasso_select"])

pglyph = p.circle(x='X', y='Y', source=source)

def callback(attr, old, new):
    # The index of the selected glyph is : new['1d']['indices'][0]
    patch_name =  source.data['X'][new['1d']['indices'][0]]
    print("LassoTool callback executed on Patch {}".format(patch_name))


pglyph.data_source.on_change('selected',callback)


curdoc().add_root(column(p))

#bokeh serve --show TestApp.py

What do I need to change to make the print function work when running this script using Bokeh Server? This will help me understand how I would be able to access the data of the selected features to use as a source for another chart.

bigreddot bigreddot · Accepted Answer · 2018-12-20T05:19:13

That linked code is very out of date. The correct way to do this with any relatively recent version of Bokeh is:

def callback(attr, old, new):
    patch_name =  source.data['X'][new]
    print("LassoTool callback executed on Patch {}".format(patch_name))

pglyph.data_source.selected.on_change('indices',callback)

Bokeh python callback to print new attribute value

1 Answers