Solutions

Author: OmarAlmighty

CH2/Checkpoints CH02/Checkpoints

@@ -0,0 +1,140 @@
+#14.1
+Tuples are like lists, but their elements are fixed; that is, once a tuple is created, you
+cannot add new elements, delete elements, replace elements, or reorder the elements in
+the tuple.
+To create a tuple from a list: t = tuple(lst)
+To create a list from a tuple: lst = list(tpl)
+
+#14.2
+t is a tuple, which its elements are fixed; we
+cannot used append and remove functions or change its content.
+
+#14.3
+Yes. Now t1 and t2 refer to the same tuple.
+
+#14.4
+(1, 2, 3, 7, 9, 0, 5)
+1
+(2, 3)
+5
+(1, 2, 3, 7, 9, 0)
+(2, 3, 7, 9, 0)
+
+#14.5
+9
+0
+27
+7
+
+#14.6
+False
+True
+False
+True
+
+#14.7
+st = set() or st = {}
+
+#14.8
+Yes.
+
+#14.9
+s = {1, 3, 4}   # Correct
+s = {{1, 2}, {4, 5}} # Incorrect, because unhashable set
+s = {[1, 2], [4, 5]} # Incorrect, because unhashable list
+s = {(1, 2), (4, 5)} # Correct (1, 2), (4, 5) are tuples. They are hashable
+
+#14.10
+Sets are like lists to store a collection of items. Unlike lists,
+the elements in a set are unique and are not placed in any particular ordered.
+To create a set from a list, use set(list). To create a list from a set, use list(set).
+
+#14.11
+{'peter', 'john'}
+{'peter', 'john'}
+{'peter', 'peterson', 'john'}
+{'peterson', 'john'}
+
+#14.12
+Yes. It will throw an exception.
+
+#14.13
+True
+False
+False
+False
+True
+True
+
+#14.14
+4
+6
+1
+16
+
+#14.15
+{1, 3, 4, 5, 6, 7}
+{1, 3, 4, 5, 6, 7}
+{1, 6}
+{1, 6}
+{4, 5}
+{4, 5}
+{3, 4, 5, 7}
+{3, 4, 5, 7}
+
+#14.16
+False
+True
+4
+11
+2
+23
+True
+True
+
+#14.17
+{1, 2, 3} {3, 4, 5} {1, 2, 3, 4, 5}
+{1, 2, 3} {3, 4, 5} {1, 2}
+{1, 2, 3} {3, 4, 5} {3}
+{1, 2, 3} {3, 4, 5} {1, 2, 4, 5}
+
+#14.18
+dict = {}
+
+#14.19
+d = {1:[1, 2], 3:[3, 4]}
+d = {1:"john", 3:"peter"}
+d = {"john":1, "peter":3}
+
+#14.20
+The two parts of a dictionary are the key and its corresponding value.
+
+#14.21
+(a) Adds a new item "susan":5
+(b) Updates the value of the key "peter" to 5
+(c) Adding 5 to the existing value of key "peter"
+(d) Delete the item with key "peter"
+
+#14.22
+(a) Prints the length of the dictionary, 2
+(b) Prints the keys of the dictionary, "john" and "peter"
+(c) Prints the values of the dictionary, 3 and 2
+(d) Prints the key/value pairs of the dictionary, {"john":3, "peter":2}
+
+#14.23
+4
+['red', 'blue', 'green', 'yellow']
+[4, 1, 14, 2]
+True
+False
+11
+
+#14.24
+5
+
+#14.25
+In case of the key does not exist in the d,
+d[key] raises an exception while d.get(key) returns None.
+
+
+

CH2/EX2.1.py CH02/EX2.1.py

@@ -0,0 +1,38 @@
+# 14.1 (Display keywords) Revise Listing 14.4 CountKeywords.py to display the keywords
+# in a Python source file as well as to count the number of the keywords.
+
+import os.path
+import sys
+
+
+def main():
+    keyWords = {"and": 0, "as": 0, "assert": 0, "break": 0, "class": 0,
+                "continue": 0, "def": 0, "del": 0, "elif": 0, "else": 0,
+                "except": 0, "False": 0, "finally": 0, "for": 0, "from": 0,
+                "global": 0, "if": 0, "import": 0, "in": 0, "is": 0, "lambda": 0,
+                "None": 0, "nonlocal": 0, "not": 0, "or": 0, "pass": 0, "raise": 0,
+                "return": 0, "True": 0, "try": 0, "while": 0, "with": 0, "yield": 0}
+
+    filename = input("Enter a Python source code filename: ").strip()
+
+    if not os.path.isfile(filename):  # Check if target file exists
+        print("File", filename, "does not exist")
+        sys.exit()
+
+    infile = open(filename, "r")  # Open files for input
+
+    text = infile.read().split()  # Read and split words from the file
+
+    count = 0
+    for word in text:
+        if word in keyWords:
+            count += 1
+            keyWords[word] += 1
+
+    print("The number of key words:", count)
+    for w in keyWords:
+        if keyWords[w] > 0:
+            print(w, ":", keyWords[w])
+
+
+main()

CH2/EX2.10.py CH02/EX2.10.py

@@ -0,0 +1,29 @@
+# 14.2 (Count occurrences of numbers) Write a program that reads an unspecified number
+# of integers and finds the ones that have the most occurrences. For example, if
+# you enter 2 3 40 3 5 4 –3 3 3 2 0, the number 3 occurs most often. Enter all numbers
+# in one line. If not one but several numbers have the most occurrences, all of
+# them should be reported. For example, since 9 and 3 appear twice in the list 9 30
+# 3 9 3 2 4, both occurrences should be reported.
+
+nums = input("Enter numbers in one line: ").split()
+
+nums_dict = {}
+
+for n in nums:
+    if n in nums_dict:
+        nums_dict[n] += 1
+    else:
+        nums_dict[n] = 0
+
+pairs = list(nums_dict.items())
+nums = [[x, y] for (y, x) in pairs]
+nums.sort(reverse=True)
+
+print(nums[0][1], end=' ')
+
+for i in range(1, len(nums)):
+    if nums[i][0] == nums[0][0]:
+        print(nums[i][1], end=' ')
+    else:
+        print()
+        break

CH2/EX2.11.py CH02/EX2.11.py

@@ -0,0 +1,43 @@
+# 14.3 (Count the occurrences of each keyword) Write a program that reads in a Python
+# source code file and counts the occurrence of each keyword in the file. Your program
+# should prompt the user to enter the Python source code filename.
+
+import os.path
+import sys
+
+
+def main():
+    keyWords = {"and": 0, "as": 0, "assert": 0, "break": 0, "class": 0,
+                "continue": 0, "def": 0, "del": 0, "elif": 0, "else": 0,
+                "except": 0, "False": 0, "finally": 0, "for": 0, "from": 0,
+                "global": 0, "if": 0, "import": 0, "in": 0, "is": 0, "lambda": 0,
+                "None": 0, "nonlocal": 0, "not": 0, "or": 0, "pass": 0, "raise": 0,
+                "return": 0, "True": 0, "try": 0, "while": 0, "with": 0, "yield": 0}
+
+    filename = input("Enter a Python source code filename: ").strip()
+
+    if not os.path.isfile(filename):  # Check if target file exists
+        print("File", filename, "does not exist")
+        sys.exit()
+
+    infile = open(filename, "r")  # Open files for input
+
+    # text = infile.read().split()  # Read and split words from the file
+    text = infile.readlines()
+    for i in range(len(text)):
+        indx = text[i].find(chr(35))  # remove comments, I use chr(35) instead of writing # directly as the # may be used in literal strings
+        if indx != -1:
+            line = text[i]
+            line = line[0:indx]
+            text[i] = line
+
+    for line in text:
+        for word in line.split():
+            if word in keyWords:
+                keyWords[word] += 1
+
+    for itm in keyWords:
+        print(itm, ":", keyWords[itm])
+
+
+main()

CH2/EX2.12.py CH02/EX2.12.py

@@ -0,0 +1,72 @@
+# 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

CH2/EX2.13.py CH02/EX2.13.py

@@ -0,0 +1,59 @@
+# 14.5 (Tkinter: Count the occurrences of each letter) Revise the preceding exercise to
+# display a histogram for the result, as shown in Figure 14.4. 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
+
+LINE_WIDTH = 23
+BASE = 350
+
+def showResult():
+    file = open(filename.get(), 'r')
+    lines = file.readlines()
+    for i in range(len(lines)):
+        lines[i] = lines[i].lower()
+    counts = [0] * 26
+    countLetters(lines, counts)
+
+    cnvs.delete("data")
+    cnvs.create_line(10, BASE, 595, BASE, tag="data")
+    x = 12
+    for i in range(26):
+        cnvs.create_text(x+2, BASE+8, text=chr(i + ord('a')),tag="data")
+        cnvs.create_rectangle(x-9, BASE-counts[i], x + LINE_WIDTH-9, BASE,tag="data")
+        x += LINE_WIDTH
+
+
+def countLetters(lines, counts):
+    for line in lines:
+        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()
+
+cnvs = Canvas(frame1, width=600,height=400)
+cnvs.pack()
+
+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