9.12. Exercises

1. Write a program that will print out the length of each item in the list as well as the first and last characters of the item.

           weather = ["sunny", "cloudy", "partially sunny",
              "rainy", "storming", "windy", "foggy",
              "snowy", "hailing"]
   ---
   for condition in weather:
   ---
       print("The word is", len(condition), "characters")
   ---
       first_char = condition[0]
       last_char = condition[-1]
   ---
       print("The first character is: " + first_char)
       print("The last character is: " + last_char)
           

2. Write code to determine how many t’s are in the following sentences.

           phrases = ["My, what a lovely day today is!",
   "Have you mastered cooking yet? A tasty treat could be in your future.",
   "Have you ever seen the leaves change color?"]
   ---
   for sentence in phrases:
   ---
       print(sentence.count("t"))
           

3. Although Python provides us with many list methods, it is good practice and very instructive to think about how they are implemented. Implement a Python function that works like the following:

   1. count

   2. in

   3. reverse

   4. index

   5. insert

   def count(obj, lst): count = 0 for e in lst: if e == obj: count = count + 1 return count def is_in(obj, lst): # cannot be called in() because in is a reserved keyword for e in lst: if e == obj: return True return False def reverse(lst): reversed = [] for i in range(len(lst)-1, -1, -1): # step through the original list backwards reversed.append(lst[i]) return reversed def index(obj, lst): for i in range(len(lst)): if lst[i] == obj: return i return -1 def insert(obj, index, lst): newlst = [] for i in range(len(lst)): if i == index: newlst.append(obj) newlst.append(lst[i]) return newlst lst = [0, 1, 1, 2, 2, 3, 4, 5, 6, 7, 8, 9] print(count(1, lst)) print(is_in(4, lst)) print(reverse(lst)) print(index(2, lst)) print(insert('cat', 4, lst))

   Show Comments

4. Write a Python function that will take a list of 100 random integers between 0 and 1000 and return the maximum value. (Note: there is a builtin function named max but pretend you cannot use it.)

   import random as r lst = [] for i in range(100): num = r.randint(1, 1000) lst.append(num) def largest(lst): #your code here ==== from unittest.gui import TestCaseGui import re class myTests(TestCaseGui): def testOne(self): output = self.getOutput().split('\n') editor = self.getEditorText().split('\n') float_re = r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?' self.assertEqual(largest(lst), max(lst), 'Checking for the list'+ str(lst)) # hardcode check self.assertFalse(re.search(r'max', self.getEditorText()), 'Checking for max') myTests().main()

   import random def max(lst): max = 0 for e in lst: if e > max: max = e return max lst = [] for i in range(100): lst.append(random.randint(0, 1000)) print(max(lst))

   Show Comments

5. Write a function sum_of_squares(xs) that computes the sum of the squares of the numbers in the list xs. For example, sum_of_squares([2, 3, 4]) should return 4+9+16 which is 29:

   def sum_of_squares(xs): # your code here ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(sum_of_squares([2,3,4]),29,"Tested sum_of_squares on input [2,3,4]") self.assertEqual(sum_of_squares([0,1,-1]),2,"Tested sum_of_squares on input [0,1,-1]") self.assertEqual(sum_of_squares([5,12,14]),365,"Tested sum_of_squares on input [5,12,14]") myTests().main()

6. Write a function to count how many odd numbers are in a list.

   def countOdd(lst): # your code here ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(countOdd([1,3,5,7,9]),5,"Tested countOdd on input [1,3,5,7,9]") self.assertEqual(countOdd([1,2,3,4,5]),3,"Tested countOdd on input [-1,-2,-3,-4,-5]") self.assertEqual(countOdd([2,4,6,8,10]),0,"Tested countOdd on input [2,4,6,8,10]") self.assertEqual(countOdd([0,-1,12,-33]),2,"Tested countOdd on input [0,-1,12,-33]") myTests().main()

   import random def countOdd(lst): odd = 0 for e in lst: if e % 2 != 0: odd = odd + 1 return odd # make a random list to test the function lst = [] for i in range(100): lst.append(random.randint(0, 1000)) print(countOdd(lst))

   Show Comments

7. Sum up all the even numbers in a list.

   def sumEven(lst): # your code here ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(sumEven([1,3,5,7,9]),0,"Tested sumEven on input [1,3,5,7,9]") self.assertEqual(sumEven([-1,-2,-3,-4,-5]),-6,"Tested sumEven on input [-1,-2,-3,-4,-5]") self.assertEqual(sumEven([2,4,6,7,9]),12,"Tested sumEven on input [2,4,6,7,9]") self.assertEqual(sumEven([0,1,12,33]),12,"Tested sumEven on input [0,1,12,33]") myTests().main()

8. Sum up all the negative numbers in a list.

   def sumNegatives(lst): # your code here ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(sumNegatives([-1,-2,-3,-4,-5]),-15,"Tested sumNegatives on input [-1,-2,-3,-4,-5]") self.assertEqual(sumNegatives([1,-3,5,-7,9]),-10,"Tested sumNegatives on input [1,-3,5,-7,9]") self.assertEqual(sumNegatives([-2,-4,6,-7,9]),-13,"Tested sumNegatives on input [-2,-4,6,-7,9]") self.assertEqual(sumNegatives([0,1,2,3,4]),0,"Tested sumNegatives on input [0,1,2,3,4]") myTests().main()

   import random def sumNegative(lst): sum = 0 for e in lst: if e < 0: sum = sum + e return sum lst = [] for i in range(100): lst.append(random.randrange(-1000, 1000)) print(sumNegative(lst))

   Show Comments

You have attempted of activities on this page