tkFileDialog is a module with open and save dialog functions. Instead of implementing those in Tkinter GUI on your own.

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Overview An overview of file dialogs:

Tkinter Open File

The askopenfilename function to creates an file dialog object. The extensions are shown in the bottom of the form (Files of type). The code below will simply show the dialog and return the filename.  If a user presses cancel the filename is empty. On a Windows machine change the initialdir to "C:\".

Python 2.7 version:

from Tkinter import *from Tkinter import *
import Tkinter, Tkconstants, tkFileDialog
root = Tk()
root.filename = tkFileDialog.askopenfilename(initialdir = "/",title = "Select file",filetypes = (("jpeg files","*.jpg"),("all files","*.*")))
print (root.filename)

Python 3 version:

from tkinter import filedialog
from tkinter import *
root = Tk()
root.filename =  filedialog.askopenfilename(initialdir = "/",title = "Select file",filetypes = (("jpeg files","*.jpg"),("all files","*.*")))
print (root.filename)

Here is an example (on Linux):

Tkinter Save File

The asksaveasfilename function prompts the user with a save file dialog.

Python 2.7 version

from Tkinter import *
import Tkinter, Tkconstants, tkFileDialog
 
root = Tk()
root.filename = tkFileDialog.asksaveasfilename(initialdir = "/",title = "Select file",filetypes = (("jpeg files","*.jpg"),("all files","*.*")))
print (root.filename)

Python 3 version

from tkinter import filedialog
from tkinter import *
root = Tk()
root.filename =  filedialog.asksaveasfilename(initialdir = "/",title = "Select file",filetypes = (("jpeg files","*.jpg"),("all files","*.*")))
print (root.filename)

Tkinter Open Directory

The askdirectory presents the user with a popup for directory selection.

Python 2.7 version

from  Tkinter import *
import Tkinter, Tkconstants, tkFileDialog
root = Tk()
root.directory = tkFileDialog.askdirectory()
print (root.directory)

tkfiledialog Tkinter askopenfilename

tkinter askdirectory

Function	Parameters	Purpose
.askopenfilename	Directory, Title, Extension	To open file: Dialog that requests selection of an existing file.
.asksaveasfilename	Directory, Title, Extension)	To save file: Dialog that requests creation or replacement of a file.
.askdirectory	None	To open directory