Chapter 16 Exercises¶

1. Fix syntax 6 errors in the code below so that the code runs correctly. It should set combined to the concatenation of start and name. It should print the length of the combined string, print the combined string, and it should print the result of name * 3.

   name = 'Mark" start = "My name is ' combined = start name print(len(combined) print(combined) print name * 3

2. Add code to line 1 so that the code below prints 14.

   a_string = b_string = "bow" c_string = (a_string + b_string) * 2 print(len(c_string))

3. Fix the 5 syntax errors in the code below so that it runs. It should print the length of my_first_list and print the result of my_first_list * 3. Then it should set my_second_list to the concatenation of my_first_list and a list containing 321.4. Then it should print the value of my_second_list.

   my_first_list = [12,"ape"13] print(len(my_first_list) print(my_firstlist * 3) my_second_list = my_first_list + [321.4 print(my_second_list

4. Fix the errors so that the procedure prints “My name is JohnJohn” and “19”.

   def name_procedure(name): start = "My name is" combined = start * (name * 2) print(combined) print(len(combined) name_procedure(John)

5. Fix 5 syntax errors in the code below so that it runs and prints the contents of items.

   def item_lister(items): items[0] = "First item' items[1] = items0] items[2] = items[2] + 1 print items item_lister([2, 4, 6 8])

6. Complete the code on lines 4 and 5 so that the function returns the average of a list of integers.

   def grade_average(a_list): sum = 0 for num in a_list: average = return average a_list = [99, 100, 74, 63, 100, 100] print(grade_average(a_list))

7. Fix the indention in the code below so that it runs correctly. It should loop and add the current value of source to so_far each time through the loop. It should also print the value of so_far each time through the loop.

   source = ["This", "is", "a", "list"] so_far = [] for index in range(0,len(source)): so_far = [source[index]] + so_far print(so_far)

8. Fix the code so that the code prints “[‘hihi’, 0, 0, 4]” .

   items = ["hi" 2, 3, 4] items[0] = items[0] * items0 items(1) = items[2] - 3 items[2] = items[1] print(items)

9. Fix 4 syntax errors in the code below. After the code executes the list so_far should contain the reverse of the source list.

   # setup the source list source = ["This","is" "a","list"] # Set the accumulator to the empty list so_far = [ # Loop through all the items in the source list for index in range(0,len(source)) # Add the current item in the source and print the current items in so_far so_far = [source[index]] + sofar print(so_far)

10. The code below currently prints the reverse of a list. Change it so that it prints a mirrored version of the list. It should print “[‘list’, ‘a’, ‘is’, ‘This’, ‘This’, ‘is’, ‘a’, ‘list’]”.

    # setup the source list source = ["This","is","a","list"] # Set the accumulator to the empty list so_far = [] # Loop through all the items in the source list for index in range(0,len(source)): # Add a list with the current item from source to so_far so_far = [source[index]] + so_far print(so_far)

11. Change the following code into a function. It should take the list and return a list of the values at the even indicies.

    numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] even_list = [] for index in range(0,len(numbers),2): even_list = even_list + [numbers[index]] print(even_list)

12. The following code creates and prints a list of even numbers. Change it and add to it so that it creates a list of all multiples of 5 from 0 to 50, inclusive.

    # initialize the variables numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] evens = [] # loop though every other index for index in range(0,len(numbers),2): # add the lists evens = evens + [numbers[index]] # print the result print(evens)

13. Change the following into a procedure. It prints a countdown from 5 to 0. Have it take the starting number for the countdown as a parameter. Print each value till it gets to 0.

    for index in range(5, -1, -1): print(index)

14. Fix the errors so that the code individually adds each item from source to new_list. Make the range decrement, so it starts from the end, but keep new_list in the same order as source.

    # initialize the variables source = ["This", "is", "a", "list"] new_list = [] # loop from the last index to the first (0) for index in range(len(source), 1, -1): # append the lists new_list = new_list + [source[index]] # print the current value of the list print(new_list)

15. Write a function that returns the values at the odd indices in a list. The function should take the number list as a parameter. If it is passed [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] for example, it should return [1, 3, 5, 7, 9].

16. Write a function that takes a list of numbers as a parameter and adds 5 to each number and returns the list.

17. Write a function that takes a list of numbers and returns the sum of the positive numbers in the list.

18. Write a function that takes in a list of numbers as a parameter. The function should calculate the sum of all the positive numbers in the list, the absolute value of the sum of the negative numbers, and return the average of the two sums.

19. Write a function to return the reverse of a list, but with only every other item from the original list starting at the end of the list. So, if it is passed the list [0,1,2,3,4,5] for example, it should return the list [5, 3, 1].

20. Write a procedure that takes an int as a parameter. The procedure should add every other odd number from 1 to the int parameter (inclusive) into a new list. The procedure should print the new list and the sum of the new list.