This plots scattering angle versus detector distance once certain variables have been entered into Entry fields and the 'plot' button has been clicked. This plot shows up in the canvas I have created. The plot method is 'def flup()', about half way down the code which is carried out by clicking the button named 'bgra'.
When I alter the variables in the entry fields then hit plot again the program adds another plot to the canvas, which is fine. What I want to do is add a button who's command is to clear the entire canvas.
Just below the plot method 'flup()' there is the start of a method named def clear() in which I want to define a function which will be used by a button to clear the canvas. That button, you'll notice, has been created a few lines below that and is called 'delete'. Could someone please give me an example of the small piece of code I will need to include in the def clear() method in order that that button will clear the canvas.
from numpy import * import matplotlib.pyplot as plt fromTkinter import * import tkMessageBox from pylab import savefig from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg,NavigationToolbar2TkAgg import matplotlib.backend_bases from matplotlib.figure import Figure def rutherford(): tkMessageBox.showinfo("hello world", j) def N(): tkMessageBox.showinfo("Variable N", "Number of alpha particles incident on foil") def T(): tkMessageBox.showinfo('Variable t', 'Thickness of foil in metres') def K(): tkMessageBox.showinfo('Variable E', 'Kinetic energy of alpha particles in joules') def atom(): tkMessageBox.showinfo('Variable Z', 'Atomic number of element from which the foil is made, or the name of the element') class App: def __init__(self, master): frame = Frame(master) #creates the first frame Button(frame, text = "?", command=N).grid(row=1,column=2) #various help buttons Button(frame, text = "?", command=T).grid(row=2,column=2) Button(frame, text = "?", command=K).grid(row=3,column=2) Button(frame, text = "?", command=atom).grid(row=4,column=2) Nlabel = Label(frame, text = "N =").grid(row=1, column=0, sticky=E) #labels next to the entry frame tlabel = Label(frame, text="t =").grid(row=2,column=0, sticky=E) Elabel = Label(frame, text="E =").grid(row=3,column=0, sticky=E) Zlabel = Label(frame, text="Z =").grid(row=4, column=0, sticky=E) eN=Entry(frame) eN.grid(row=1,column=1) et=Entry(frame) et.grid(row=2,column=1) eE=Entry(frame) eE.grid(row=3,column=1) eZ=Entry(frame) eZ.grid(row=4,column=1) def flup(): #the plot N=float(eN.get())#turn string into float t=float(et.get()) E=float(eE.get()) Z=float(eZ.get()) r=10*(10**-10) e=1.602*(10**-19) a=5*(10**30) i = linspace(math.pi/80, math.pi, 1000) list = for p in i: b = (N*a*t)/(16.0*(r**2)) c = ((2.0*Z*(e**2))/(E*4.0*math.pi*8.854*(10**-12)))**2 d = (1.0/(math.sin(p/2.0)))**4 n=b*c*d list.append(n) f=Figure(figsize=(5,4), dpi=100) g=f.add_subplot(1,1,1) g.plot(i,list) canvas=FigureCanvasTkAgg(f, master=master) canvas.show() canvas.get_tk_widget().pack(side=LEFT, fill=BOTH, expand=1) canvas._tkcanvas.pack(side=TOP, fill=BOTH, expand=1) #def clear(): bgra=Button(frame, text = "Plot", command=flup) #this button makes the plot bgra.grid(row=5,column=1) delete=Button(frame,text='Clear All', command=clear) delete.grid(row=5,column=2) frame2=Frame(master) b1=Button(frame2, text="Rutherford Scattering??", command=rutherford) b1.pack(side=LEFT) frame2.pack() frame.pack() root = Tk() app = App(root) root.mainloop()
To delete everything on a canvas, call the
delete method with an argument of
"all". I don't know anything about matplotlib, but I'm guessing you would do something like this: