bokeh selected.on_change not working for my current setup - bokeh

Question

Basically, this is an interactive heatmap but the twist is that the source is updated by reading values from a file that gets updated regularly.
dont bother about the class "generator", it is just for keeping data and it runs regularly threaded
make sure a file named "Server_dump.txt" exists in the same directory of the script with a single number greater than 0 inside before u execute the bokeh script.
what basically happens is i change a number inside the file named "Server_dump.txt" by using echo 4 > Server_dump.txt on bash,
u can put any number other than 4 and the script automatically checks the file and plots the new point.
if u don't use bash, u could use a text editor , replace the number and save, and all will be the same.
the run function inside the generator class is the one which checks if this file was modified , reads the number, transforms it into x& y coords and increments the number of taps associated with these coords and gives the source x,y,taps values based on that number.
well that function works fine and each time i echo a number , the correct rectangle is plotted but,
now I want to add the functionality of that clicking on a certain rectangle triggers a callback to plot a second graph based on the coords of the clicked rectangle but i can't even get it to trigger even though i have tried other examples with selected.on_change in them and they worked fine.
*if i increase self.taps for a certain rect by writing the number to the file multiple times, color gets updated but if i hover over the rect it shows me the past values and not the latest value only .
my bokeh version is 1.0.4
from functools import partial
from random import random,randint
import threading
import time
from tornado import gen
from os.path import getmtime
from math import pi
import pandas as pd
from random import randint, random
from bokeh.io import show
from bokeh.models import LinearColorMapper, BasicTicker, widgets, PrintfTickFormatter, ColorBar, ColumnDataSource, FactorRange
from bokeh.plotting import figure, curdoc
from bokeh.layouts import row, column, gridplot
source = ColumnDataSource(data=dict(x=[], y=[], taps=[]))
doc = curdoc()
#sloppy data receiving function to change data to a plottable shape
class generator(threading.Thread):
def __init__(self):
super(generator, self).__init__()
self.chart_coords = {'x':[],'y':[],'taps':[]}
self.Pi_coords = {}
self.coord = 0
self.pos = 0
self.col = 0
self.row = 0
self.s = 0
self.t = 0
def chart_dict_gen(self,row, col):
self.col = col
self.row = row+1
self.chart_coords['x'] = [i for i in range(1,cla.row)]
self.chart_coords['y'] = [i for i in range(cla.col, 0, -1)] #reversed list because chart requires that
self.chart_coords['taps']= [0]*(row * col)
self.taps = [[0 for y in range(col)] for x in range(row)]
def Pi_dict_gen(self,row,col):
key = 1
for x in range(1,row):
for y in range(1,col):
self.Pi_coords[key] = (x,y)
key = key + 1
def Pi_to_chart(self,N):
x,y = self.Pi_coords[N][0], self.Pi_coords[N][1]
return x,y
def run(self):
while True:
if(self.t == 0):
self.t=1
continue
time.sleep(0.1)
h = getmtime("Server_dump.txt")
if self.s != h:
self.s = h
with open('Server_dump.txt') as f:
m = next(f)
y,x = self.Pi_to_chart(int(m))
self.taps[x][y] += 1
# but update the document from callback
doc.add_next_tick_callback(partial(update, x=x, y=y, taps=self.taps[x][y]))
cla = generator()
cla.chart_dict_gen(15,15)
cla.Pi_dict_gen(15, 15)
x = cla.chart_coords['x']
y = cla.chart_coords['y']
taps = cla.chart_coords['taps']
#gen.coroutine
def update(x, y, taps):
taps += taps
print(x,y,taps)
source.stream(dict(x=[x], y=[y], taps=[taps]))
colors = ["#CCEBFF","#B2E0FF","#99D6FF","#80CCFF","#66c2FF","#4DB8FF","#33ADFF","#19A3FF", "#0099FF", "#008AE6", "#007ACC","#006BB2", "#005C99", "#004C80", "#003D66", "#002E4C", "#001F33", "#000F1A", "#000000"]
mapper = LinearColorMapper(palette=colors, low= 0, high= 15) #low = min(cla.chart_coords['taps']) high = max(cla.chart_coords['taps'])
TOOLS = "hover,save,pan,box_zoom,reset,wheel_zoom"
p = figure(title="Tou",
x_range=list(map(str,x)),
y_range=list(map(str,reversed(y))),
x_axis_location="above",
plot_width=900, plot_height=400,
tools=TOOLS, toolbar_location='below',
tooltips=[('coords', '#y #x'), ('taps', '#taps%')])
p.grid.grid_line_color = "#ffffff"
p.axis.axis_line_color = "#ef4723"
p.axis.major_tick_line_color = "#af0a36"
p.axis.major_label_text_font_size = "7pt"
p.xgrid.grid_line_color = None
p.ygrid.grid_line_color = None
p.rect(x="x", y="y",
width=0.9, height=0.9,
source=source,
fill_color={'field': 'taps', 'transform': mapper},
line_color = "#ffffff",
)
color_bar = ColorBar(color_mapper=mapper,
major_label_text_font_size="7pt",
ticker=BasicTicker(desired_num_ticks=len(colors)),
formatter=PrintfTickFormatter(format="%d%%"),
label_standoff=6, border_line_color=None, location=(0, 0))
curdoc().theme = 'dark_minimal'
def ck(attr, old, new):
print('here') #doesn't even print hi in the terminal if i click anywhere
source.selected.on_change('indices', ck)
p.add_layout(color_bar, 'right')
doc.add_root(p)
thread = cla
thread.start()
i wanted even to get a printed hi in the terminal but nothing

Answer 1

You have not actually added any selection tool at all to your plot, so no selection is ever made. You have specified:
TOOLS = "hover,save,pan,box_zoom,reset,wheel_zoom"
Those are the only tools that will be added, and none of them make selections, there for nothing will cause source.selection.indices to ever be updated. If you are looking for selections based on tap, you must add a TapTool, e.g. with
TOOLS = "hover,save,pan,box_zoom,reset,wheel_zoom,tap"
Note that there will not be repeated callbacks if you tap the same rect multiple times. The callback only fires when the selection changes and clicking the same glyph twice in a row results in an identical selection.