Reading assignment:

• Chapter 4, pages 73-74 (Sorting and Searching)
  • Example from page 73, converted to Python 3
• Chapter 8, pages 129-130 (List Comprehensions)
• Chapter 6, pages 100-102 (File Input)

Programming problems

• Place all functions in a single file called hw7.py.

Searching and Sorting

• Page 87, problem 34. Implement binary search, as described in the second paragraph on page 73 of the textbook.
  Function declaration: def bisect(lst, ele):
  Return value: It will return the position in lst where the element could be inserted without violating the sorted ordering.
  

  >>> bisect([], 12)
  0
  >>> bisect([1,3,5,7], 0)
  0
  >>> bisect([1,3,5,7], 1)
  1
  >>> bisect([1,3,5,7], 2)
  1
  >>> bisect([1,3,5,7], 3)
  2
  >>> bisect([1,3,5,7], 4)
  2
  >>> bisect([1,3,5,7], 5)
  3
  >>> bisect([1,3,5,7], 6)
  3
  >>> bisect([1,3,5,7], 7)
  4
  >>> bisect([1,3,5,7], 8)
  4
  

• Write a function called insert(lst, ele) that takes two arguments: a list and an element (just like bisect()). You should assume that lst is sorted. The function will not return anything; instead, it will add ele to lst while keeping lst sorted. You may call bisect(lst, ele) as part of your solution if you find it helpful, but you are not required to do so.

  >>> lst = [1,3,5,7]
  >>> insert(lst, 0)
  >>> lst
  [0, 1, 3, 5, 7]
  >>> insert(lst, 2)
  >>> lst
  [0, 1, 2, 3, 5, 7]
  >>> insert(lst, 6)
  >>> lst
  [0, 1, 2, 3, 5, 6, 7]
  >>> insert(lst, 8)
  >>> lst
  [0, 1, 2, 3, 5, 6, 7, 8]
  >>> insert(lst, 4)
  >>> lst
  [0, 1, 2, 3, 4, 5, 6, 7, 8]
  >>> insert(lst, 5)
  [0, 1, 2, 3, 4, 5, 5, 6, 7, 8]
  

• Write a function called insertionSort(lst) that takes an arbitrary list as an argument and returns a new list that contains all the elements of the original list in sorted order. The parameter lst will not be modified. It is strongly recommended that you call insert() as part of your solution.

  >>> lst = [5, 3, 8, 2, 1, 0, 5, 6]
  >>> insertionSort(lst)
  [0, 1, 2, 3, 5, 5, 6, 8]
  >>> lst
  [5, 3, 8, 2, 1, 0, 5, 6]
  

Other Chapter 4 Problems

• Page 84, problem 17. Write a function called stumble2() to implement this program.
  Unlike problem 16, you should only print the array after the last step of the simulation. When you print the array, print each row individually, so that the printed array is aligned as shown in the example below. You should also return the list.

  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
  [0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0]
  [0, 0, 0, 0, 2, 2, 0, 0, 0, 0, 0]
  [0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0]
  [0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0]
  [0, 0, 1, 2, 1, 1, 0, 0, 0, 0, 0]
  [0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0]
  

• Page 86, problem 29.
  Function declaration: def randomElement(lst):
  Return value: It will return a randomly selected element from lst.
  Given any list lst, randomElement(lst) in lst should always evaluate to True.
  Hint: If your solution contains a for loop, while loop, or an if statement, it is incorrect!

  >>> randomElement([12,34,56,78,90])
  34
  >>> randomElement([12,34,56,78,90])
  90
  >>> randomElement([12,34,56,78,90])
  12
  >>> randomElement(['hello', 'goodbye', 'greetings', 'salutations'])
  'greetings'
  

• Page 87, problem 32.
  Function declaration: def polygonArea(poly):
  Return value: It will return the area of poly.
  Note: The book's formula for the area of a triangle does not always work; instead, use: abs(x₁ y₂ + x₂ y₃ + x₃ y₁ - x₂ y₁ - x₃ y₂ - x₁ y₃) / 2

  >>> polygonArea([(0, 0), (0, 4), (4, 4), (4, 0)])
  16.0
  >>> polygonArea([(0, 0), (2, 2), (4, 0)])
  4.0
  >>> polygonArea([(0, 0), (0, 4), (2, 6), (4, 4), (4, 0)])
  20.0
  >>> polygonArea([(2, 0), (4, 1), (3, 2), (1, 3), (-1, 2), (-2, 1), (0, 0)])
  11.0
  

List Comprehension Problems

• squares
• smaller
• multBy
• lowerCase
• stripped
• onlyWith
• Writing these functions may require using two list comprehensions:
  • strings2points
  • splitUp

File Input Problems:

• For each of these problems, the file test.txt was used for generating each example below.
• Page 110, problem 1:

  >>> comment_lines('test.txt')
  ['# This is a test file for our file I/O.\n', '# This line is another comment line.\n']
  

• Page 110, problem 2:

  >>> sorted_lines('test.txt')
  ['# This is a test file for our file I/O.\n', '# This line is another comment line.\n', 'A fifth line might clarify issues further.\n', 'Another line is given here to help test sorting.\n', 'This is the second line of the aforementioned file.\n']
  

• Page 110, problem 6:

  >>> counter('test.txt')
  (221, 42, 5)
  

• Page 110, problem 8:

  >>> only_with('test.txt', 'This')
  ['# This is a test file for our file I/O.\n', 'This is the second line of the aforementioned file.\n', '# This line is another comment line.\n']
  

Additional problems

• Pages 110-111, 3-4.