Change Entry widget value from other function - python-3.x

Question

I am quite new in programming with tkinter , especially with classes. How can I make a button that runs function from the same class and changes entry widget. In my code i want to change entry1 whenever button1 is clicked and filepath function runs.
thank you for your help.
Class Example(Frame):
def __init__(self):
super().__init__()
self.initUI()
def filepath():
filename = fd.askopenfilename()
entry1.delete(0,END)
entry1.insert(0,filename)
def initUI(self):
self.master.title("EFEKTYWNOŚĆ APP")
self.pack(fill=BOTH, expand=True)
cd = (os.getcwd())
frame1 = Frame(self)
frame1.pack(side = LEFT)
lbl1 = Label(frame1,
text="...",
wraplength = 250 )
lbl1.pack(side=LEFT, padx=5, pady=5)
path = os.path.join(cd, 'ico', '...')
photo = PhotoImage(file = path)
cphoto = photo.subsample(4,4)
button1 = Button(frame1,
text='WYBIERZ PLIK',
image = cphoto,
compound = LEFT,
command = Example.filepath)
button1.image = cphoto
button1.pack(side=LEFT, fill = Y, padx=5, pady=5)
entry1 = Entry(frame1)
entry1.pack(side=LEFT, fill = Y, padx=5, pady=5)

Answer 1

There are some minor things needed to be fixed in your code. I have added a working sample with comments below.
from tkinter import *
from tkinter import filedialog as fd
import os
class Example(Frame):
def __init__(self, master,**kwargs): #have your Frame accept parameters like how a normal frame should
super().__init__(master,**kwargs)
self.master = master #set master as an attribute so you can access it later
self.initUI()
def filepath(self): #add self to make the method an instance method
filename = fd.askopenfilename()
self.entry1.delete(0, END) #use self when referring to an instance attribute
self.entry1.insert(0, filename)
def initUI(self):
self.master.title("EFEKTYWNOŚĆ APP")
self.pack(fill=BOTH, expand=True)
cd = (os.getcwd())
frame1 = Frame(self)
frame1.pack(side=LEFT)
lbl1 = Label(frame1,
text="...",
wraplength=250)
lbl1.pack(side=LEFT, padx=5, pady=5)
path = os.path.join(cd, 'ico', '...')
photo = PhotoImage(file=path)
cphoto = photo.subsample(4, 4)
button1 = Button(frame1,
text='WYBIERZ PLIK',
image=cphoto,
compound=LEFT,
command=self.filepath) #refer to instance methods by self.your_method
button1.pack(side=LEFT, fill=Y, padx=5, pady=5)
self.entry1 = Entry(frame1) #add self to make it an instance attribute
self.entry1.pack(side=LEFT, fill=Y, padx=5, pady=5) #you will then need to use self.entry1 within your class instance
root = Tk()
Example(root)
root.mainloop()