Get the selected range from a boxselect tool

Community Support
1

I am aware that when using the BoxSelectTool, you can get the indices of the selected data in a ColumnDataSource callback with:

source.callback = CustomJS(args=dict(),code="""
var inds = cb_obj.get(‘selected’)[‘1d’].indices;
“”")

``

However I would like to get information on the selection box itself, instead of information on the data in the box. How can I get the xmin and xmax of the current selection of a BoxSelectTool?

2

Just to add some precisions. I also know about the cb_data[‘geometry’] you can get from the callback of the boxselecttool itself. But this doesn’t give xmin and xmax of the selection in data coordinates.

3

I realized selection coordinates in cb_data[“geometry”] are already in data coordinates, for a datetime axis the returned values are milliseconds since epoch. So here is a small code that displays the selection range in text:

from bokeh.plotting import Figure, output_file

from bokeh.models import CustomJS, ColumnDataSource, PreText

from bokeh.layouts import gridplot

from bokeh.resources import CDN

from bokeh.embed import file_html

import os

import datetime

wdir = os.getcwd()

start_date = datetime.datetime(2010,1,1)

date_list = [start_date + datetime.timedelta(days=x) for x in range(0,365)]

y = range(len(date_list))

TOOLS = “pan,wheel_zoom,box_zoom,undo,redo,reset,box_select,save”

fig = Figure(plot_height=400,plot_width=400,tools=TOOLS,x_axis_type=‘datetime’)

txt=PreText(text=‘Selection range:’,width=1000)

fig.tools[-2].callback = CustomJS(args=dict(txt=txt),code="""

var sel = cb_data["geometry"];

var startsec = sel["x0"]/1000;

var start = new Date(0);

start.setUTCSeconds(startsec)

var startstring = ("0" + start.getDate()).slice(-2) + "-" + ("0"+(start.getMonth()+1)).slice(-2) + "-" +start.getFullYear() + " " + ("0" + start.getHours()).slice(-2) + ":" + ("0" + start.getMinutes()).slice(-2);

var finishsec = sel["x1"]/1000;

var finish = new Date(0);

finish.setUTCSeconds(finishsec)

var finishstring = ("0" + finish.getDate()).slice(-2) + "-" + ("0"+(finish.getMonth()+1)).slice(-2) + "-" +finish.getFullYear() + " " + ("0" + finish.getHours()).slice(-2) + ":" + ("0" + finish.getMinutes()).slice(-2);

txt.text = 'Selection range from '+startstring + ' to ' + finishstring;

txt.trigger("change");

""")

fig.scatter(x=date_list,y=y)

grid = gridplot([[txt],[fig]],toolbar_location=‘left’)

outfile=open(os.path.join(wdir,‘boktest.html’),‘w’)

outfile.write(file_html(grid,CDN,‘test’))

outfile.close()

``