Cannot remove one of the x-ticks from a 2x1 subplot.

[generalzu10]

Hi. I posted this question on Stack Exchange, and I am posting it here as well incase anyone can help here.

I will post the full text here. Any help is appreciated.

--------------------------------------------------------------------
I am making a GUI which shows a graph of 4 different readings. Right now the readings are randomly generated. I am using matplotlib and animation to show live readings, where 2 of the readings are sharing one subplot, and the other two are shown on the other subplot. On the x-axis, I am showing the current time readings.

I am relatively new to python, so I am not sure how some of the stuff works. My issue is most likely that I have the answers but don't know how to apply them.

Here is my code:

import tkinter as tk 
from tkinter import *
from tkinter import ttk

import matplotlib 
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2Tk
import matplotlib.pyplot as plt #to plot the graph
import matplotlib.animation as animation #to create the real-time graph
from matplotlib import style #to change the way the graph will look
import matplotlib.ticker as mticker

import numpy as np
import datetime as dt

#-----------------------------END OF IMPORT -----------------------------------------------#
matplotlib.use("TkAgg") #backend of matplotlib??
style.use("dark_background") 
LARGE_FONT = ("Times New Roman", 12)
NORM_FONT = ("Times New Roman", 9)
colors = ('tab:red','tab:blue')
#----------------------------------FUNCTION------------------------------------------------#

fig1 = plt.figure(0)
ax11 = fig1.add_subplot(211)

ax12 = ax11.twinx()

ax21 = fig1.add_subplot(212,sharex=ax11)
ax22 = ax21.twinx()

xList1= []
yList11=[]
yList12=[]

xList2= []
yList21=[]
yList22=[]


def animate_graph(i,x1,y11,y12,ax11
                  ,ax12
                  ,x2
                  ,y21,y22,ax21,ax22
                  ):


    a = (2-1)*np.random.random()+1
    b = (4-3)*np.random.random()+3
    c = (6-5)*np.random.random()+5
    d = (8-7)*np.random.random()+7


    x1.append(dt.datetime.now().strftime('%H:%M:%S'))
    y11.append(a)
    y12.append(b)

    x2.append(dt.datetime.now().strftime('%H:%M:%S'))
    y21.append(c)
    y22.append(d)


    x1 = x1[-10:]
    y11 = y11[-10:]
    y12 = y12[-10:]

    x2 = x2[-10:]
    y21 = y21[-10:]
    y22 = y22[-10:]


    ax11.clear()
    ln1 = ax11.plot(x1,y11,colors[0],label = 'Temp(C)')
    ax11.tick_params(axis = 'y',labelcolor = colors[0])


    ax12.clear()
    ln2 = ax12.plot(x1,y12,colors[1],label = 'RH(%?)')
    ax12.tick_params(axis = 'y',labelcolor = colors[1])


    lns1 = ln1 + ln2
    labs1 = [l.get_label() for l in lns1]
    ax11.legend(lns1,labs1,bbox_to_anchor = (0,1.02,1,0.102),loc = 3,ncol = 3,borderaxespad = 0)

    ax21.clear()
    ln3 = ax21.plot(x2,y21,colors[0],label = 'CO(%)')
    ax21.tick_params(axis = 'y',labelcolor = colors[0])
    

    ax22.clear()
    ln4 = ax22.plot(x2,y22,colors[1],label = 'CO2(%)')

    ax22.tick_params(axis = 'y',labelcolor = colors[1])

    lns2 = ln3 + ln4
    labs2 = [l.get_label() for l in lns2]
    ax21.legend(lns2,labs2,bbox_to_anchor = (0,1.02,1,0.102),loc = 3,ncol = 3,borderaxespad = 0)

    ax11.tick_params(axis = 'x',labelrotation = 45)
    
    ax21.tick_params(axis = 'x',labelrotation = 45)

#----------------------------------MAIN-------------------------------#
class main(tk.Tk):
    
    def __init__(self, *args, **kwargs):

        tk.Tk.__init__(self,*args,**kwargs)
        tk.Tk.title(self, "Hubba Dub")
        
        container = tk.Frame(self)
        container.pack(side = "top" , fill = "both" , expand = True)
        container.grid_rowconfigure(0, weight = 1)
        container.grid_columnconfigure(0,weight = 1)

        menubar = tk.Menu(self,tearoff=0)

        filemenu = menubar.add_command(label= "Exit", command=quit)
        menubar.add_cascade(label="File",menu= filemenu)

        playpausemenu = menubar.add_command(label= "Pause", command=0)
        menubar.add_cascade(label  = "Pause/Play",menu=playpausemenu)


        self.frames = {}

        for f in (StartPage,GraphAll):
            frame = f(container,self)
            self.frames[f] = frame
            frame.grid(row = 0,column = 0, sticky = "nsew")

        self.show_frame(StartPage)

    def show_frame(self,cont):
        frame = self.frames[cont]
        frame.tkraise()

class StartPage(tk.Frame):
    
    def __init__(self,parent,control):
        tk.Frame.__init__(self,parent)

        label = ttk.Label(self,text = "StartPage", font = LARGE_FONT)
        label.pack(pady = 10, padx = 10)
        
        b1 = ttk.Button(self,text = "Open page to display sensor data", command = lambda: control.show_frame(GraphAll))
        b1.pack()

        b3 = ttk.Button(self,text = "Exit", command = quit)
        b3.pack()

class GraphAll(tk.Frame):
    def __init__(self,parent,control):
        tk.Frame.__init__(self,parent)
        
        label = ttk.Label(self,text = "Show All Readings",font = LARGE_FONT)
        label.pack()

        b1 = ttk.Button(self,text = "Pause", command = lambda: anim.event_source.stop())
        b1.pack()

        b2 = ttk.Button(self,text = "Play", command = lambda: anim.event_source.start())
        b2.pack()

        b3 = ttk.Button(self,text = "Exit",command= quit)
        b3.pack()

        canvas = FigureCanvasTkAgg(fig1,self)
        canvas.draw()
        canvas.get_tk_widget().pack(side=tk.TOP,fill = tk.BOTH,expand = True)

        toolbar = NavigationToolbar2Tk(canvas,self)
        toolbar.update()
        canvas._tkcanvas.pack(side=tk.TOP,fill = tk.BOTH,expand = True)



# call main class
gui = main()   
# gui.geometry("1280x720")
gui.state('zoomed') #maximise window
anim = animation.FuncAnimation(fig1,animate_graph,
                               fargs=(xList1,yList11,yList12,ax11
                                      ,ax12
                                      ,xList2,yList21,yList22,ax21,ax22
                                      )
                                      ,interval= 1000
                                      )
#run in loop
gui.mainloop()

This is the image of the plot You can see the readings here are showing up correctly. The only issue is the x-axis readings are showing up on both instead of just one.

I thought by using sharex, it would show only show the x-axis on the bottom plot, rather than the top, but that didn't change anything, which is surprising to me because that should have worked.

I tried to use set_xticks([]) but I don't see any change. Maybe I am not doing it right but I am not sure where the issue actually is.

I found out about get_xticklines() from this question but that doesn't seem to work either.

[generalzu10]

I figured out the problem. I posted my answer to Stack Exchange. Just gonna leave a copy here.

#setup second axis of plot 2
    ax22.clear()
    ln4 = ax22.plot(x2,y22,colors[1],label = 'CO2(%)')
    ax22.tick_params(axis = 'y',labelcolor = colors[1])

    #---------------------------------------------#
    #set the x-axis tick labels visibility to False
    plt.setp(ax21.get_xticklabels(),visible = False)
    #----------------------------------------------#
    
    #keep two legends from the two axes together. legends belong to an axis. In our case, we have two y-axis, so two separate legend made rather than together
    lns2 = ln3 + ln4
    labs2 = [l.get_label() for l in lns2]
    ax21.legend(lns2,labs2,bbox_to_anchor = (0,-0.1,1,0)
                # (0,1.02,1,0.102)
                ,loc = 'lower left',ncol = 3,borderaxespad = 0)

Final picture:

What changed: added the line plt.setp(ax21.get_xticklabels(),visible = False) and change bbox_to_anchor parameters to (0,-0.1,1,0)