I have an application where I want to change the colors used to map a plot with (x,y,z) points dynamically. I created the following to demonstrate the basic idea.

import matplotlib.pyplot as plt 
import numpy as np 
import matplotlib as mpl 
import tkinter as tk 
from matplotlib.backends.backend_tkagg 
import FigureCanvasTkAgg

class colorbar_app(tk.Tk):

def __init__(self):
    
    super().__init__()

    # create FigureCanvasTkAgg object containing a plot
    self.fig, self.axes = plt.subplots(1,1,figsize=(8,6), 
                                       layout='constrained')
    self.axes.plot(np.random.randn(1000), 'bo')
    self.fig_canvas = FigureCanvasTkAgg(self.fig, self)
    self.fig_canvas.draw()
   
    # # Create stand-alone color bar figure plot
    self.fig2, self.cbar_ax = plt.subplots(figsize=(8,0.75), 
                                               layout='constrained')
    # Colorbar in a separate canvas
    self.cmap = mpl.cm.rainbow
    self.vmin, self.vmax = (0,10)
    self.norm = mpl.colors.Normalize(vmin=self.vmin, vmax=self.vmax)
    # Insert the colorbar into the colorbar figure
    xx = mpl.cm.ScalarMappable(norm=self.norm, cmap=self.cmap)
    self.cbar = self.fig2.colorbar(xx, cax=self.cbar_ax, 
                                   orientation='horizontal', 
                                   label = 'XXXX')
    self.cbar_canvas = FigureCanvasTkAgg(self.fig2, self)

    self.custom_toolbar()  # create a custom toolbar

    self.fig_canvas.get_tk_widget().pack() 
    self.cbar_canvas.get_tk_widget().pack() 
    self.toolbar.pack(side=tk.LEFT)                             
    
def custom_toolbar(self):
    
    self.toolbar = tk.Frame(self.master, bd=1, relief=tk.RAISED) 
    self.colorbyLabel = tk.Label(self.toolbar, text='ColorBy: ')       
    self.moreButton = tk.Button(self.toolbar, text='MORE', bg='light green',
                          command=self.on_more_button)       
    self.colorbyLabel.pack(side=tk.LEFT, padx=2, pady=2)
    self.moreButton.pack(side=tk.LEFT, padx=2, pady=2)
    
def on_more_button(self):
    print('MORE button pressed')
    self.vmin, self.vmax = self.vmin*2, self.vmax*2
    self.norm = mpl.colors.Normalize(vmin=self.vmin, vmax=self.vmax)
    xx = mpl.cm.ScalarMappable(norm=self.norm, cmap=self.cmap)
    self.cbar = self.fig2.colorbar(xx, cax=self.cbar_ax, 
                                   orientation='horizontal', 
                                   label = 'MORE')
    self.cbar.set_ticks(np.linspace(self.vmin, self.vmax, 100))

app = colorbar_app() 
app.mainloop()

This creates the general idea – a plot window with a colorbar below and a toolbar with buttons below that. I used a simple plot rather than the LineCollections I actually plot. These can be colorized, the plot I have here … not so much.

When I press the button, I want to change the colormap range used to (eventually) replot the data on the top but I can’t figure out how to get the colorbar to display the new range, or a new label. Didn’t find anything on-line on how to do this, but I did write an app 10 years ago that did accomplish this. Can’t recall how I did it before. Any suggestions?

I tried cbar.set_ticks(), tried to change clims .. but just can’t find the right combination.