Answer
code
Work Step by Step
# 14.4 (Tkinter: Count the occurrences of each letter) Rewrite Listing 14.5 using a GUI
# program to let the user enter the file from an entry field, as shown in Figure 14.3a.
# You can also select a file by clicking the Browse button to display an Open file dialog
# box, as shown in Figure 14.3b. The file selected is then displayed in the entry
# field. Clicking the Show Result button displays the result in a text widget. You
# need to display a message in a message box if the file does not exist.
from tkinter import * # Import tkinter
import tkinter.messagebox # Import tkinter.messagebox
from tkinter.filedialog import askopenfilename
def showResult():
analyzeFile(filename.get())
def analyzeFile(filename):
try:
infile = open(filename, "r") # Open the file
counts = 26 * [0] # Create and initialize counts
for line in infile:
# Invoke the countLetters function to count each letter
countLetters(line.lower(), counts)
# Display results
for i in range(len(counts)):
if counts[i] != 0:
text.insert(END, chr(ord('a') + i) + " appears " + str(counts[i])
+ (" time" if counts[i] == 1 else " times") + "\n")
infile.close() # Close file
except IOError:
tkinter.messagebox.showwarning("Analyze File",
"File " + filename + " does not exist")
# Count each letter in the string
def countLetters(line, counts):
for ch in line:
if ch.isalpha():
counts[ord(ch) - ord('a')] += 1
def openFile():
filenameforReading = askopenfilename()
filename.set(filenameforReading)
window = Tk() # Create a window
window.title("Occurrence of Letters") # Set title
frame1 = Frame(window) # Hold four labels for displaying cards
frame1.pack()
scrollbar = Scrollbar(frame1)
scrollbar.pack(side=RIGHT, fill=Y)
text = Text(frame1, width=40, height=10, wrap=WORD,
yscrollcommand=scrollbar.set)
text.pack()
scrollbar.config(command=text.yview)
frame2 = Frame(window) # Hold four labels for displaying cards
frame2.pack()
Label(frame2, text="Enter a filename: ").pack(side=LEFT)
filename = StringVar()
Entry(frame2, width=20, textvariable=filename).pack(side=LEFT)
Button(frame2, text="Browse", command=openFile).pack(side=LEFT)
Button(frame2, text="Show Result", command=showResult).pack(side=LEFT)
window.mainloop() # Create an event loop
