How to update a plot in pyqtgraph?

I am trying to have a user interface using PyQt5 and pyqtgraph. I made two checkboxes and whenever I select them I want to plot one of the two data sets available in the code and whenever I deselect a button I want it to clear the corresponding curve. There are two checkboxes with texts A1 and A2 and each of them plot one set of data.

I have two issues:

1- If I select A1 it plots the data associated with A1 and as long as I do not select A2, by deselecting A1 I can clear the data associated with A1. However, If I check A1 box and then I check A2 box, then deselecting A1 does not clear the associated plot. In this situation, if I choose to plot random data, instead of a deterministic curve such as sin, I see that by selecting either button new data is added but it cannot be removed.

2- The real application have 96 buttons each of which should be associated to one data set. I think the way I wrote the code is inefficient because I need to copy the same code for one button and data set 96 times. Is there a way to generalize the toy code I presented below to arbitrary number of checkboxes? Or perhaps, using/copying the almost the same code for every button is the usual and correct way to do this?

The code is:

from PyQt5 import QtWidgets, uic, QtGui
import matplotlib.pyplot as plt
from matplotlib.widgets import SpanSelector
import numpy as np
import sys
import string
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, QtCore

app = QtWidgets.QApplication(sys.argv)

x = np.linspace(0, 3.14, 100)
y1 = np.sin(x)#Data number 1 associated to checkbox A1
y2 = np.cos(x)#Data number 2 associated to checkbox A2

#This function is called whenever the state of checkboxes changes
def todo():
    if cbx1.isChecked():
        global curve1
        curve1 = plot.plot(x, y1, pen = 'r')
    else:
        try:
            plot.removeItem(curve1)
        except NameError:
            pass
    if cbx2.isChecked():
        global curve2
        curve2 = plot.plot(x, y2, pen = 'y')
    else:
        try:
            plot.removeItem(curve2)
        except NameError:
            pass  
#A widget to hold all of my future widgets
widget_holder = QtGui.QWidget()

#Checkboxes named A1 and A2
cbx1 = QtWidgets.QCheckBox()
cbx1.setText('A1')
cbx1.stateChanged.connect(todo)

cbx2 = QtWidgets.QCheckBox()
cbx2.setText('A2')
cbx2.stateChanged.connect(todo)

#Making a pyqtgraph plot widget
plot = pg.PlotWidget()

#Setting the layout
layout = QtGui.QGridLayout()
widget_holder.setLayout(layout)

#Adding the widgets to the layout
layout.addWidget(cbx1, 0,0)
layout.addWidget(cbx2, 0, 1)
layout.addWidget(plot, 1,0, 3,1)

widget_holder.adjustSize()
widget_holder.show()

sys.exit(app.exec_())


    

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