Introduction to Computer Science and Programming in Python

Lecture 5

1. Tuples

   Examine the code below. What does always_sunny(('cloudy'), ('cold',)) evaluate to?

   def always_sunny(t1, t2):
    """ t1, t2 are non empty """
    sun = ("sunny","sun")
    first = t1[0] + t2[0]
    return (sun[0], first)
   

   (‘sunny’, ‘cc’) close

   (‘sunny’, ‘ccold’) check

   (‘sunny’, ‘cloudycold’) close

   Check   Show Solution

2. Simple Lists

   What is the value of L after you run the code below?

   L = ["life", "answer", 42, 0]
   for thing in L:
    if thing == 0:
     L[thing] = "universe"
    elif thing == 42:
     L[1] = "everything"
   

   [“life”, “answer”, 42, 0] close

   [“universe”, “answer”, 42, 0] close

   [“universe”, “everything”, 42, 0] check

   [“life”, “everything”, 42, 0] close

   Check   Show Solution

3. List Operations

   What is the value of L3 after you execute all the operations in the code below?

   L1 = ['re']
   L2 = ['mi']
   L3 = ['do']
   L4 = L1 + L2
   L3.extend(L4)
   L3.sort()
   del(L3[0])
   L3.append(['fa','la'])
   

   [‘mi’, ’re’, [‘fa’, ’la’]] check

   [‘mi’, ’re’, ‘fa’, ’la’] close

   [’re’, ‘mi’, [‘fa’, ’la’]] close

   [‘do’, ‘mi’, [‘fa’, ’la’]] close

   Check   Show Solution

4. List Aliasing/Mutation

   What is the value of brunch after you execute all the operations in the code below?

   L1 = ["bacon", "eggs"]
   L2 = ["toast", "jam"]
   brunch = L1
   L1.append("juice")
   brunch.extend(L2)
   

   [‘bacon’, ’eggs’, ’toast’, ‘jam’] close

   [‘bacon’, ’eggs’, ‘juice’, ’toast’, ‘jam’] check

   [‘bacon’, ’eggs’, ‘juice’, [’toast’, ‘jam’]] close

   [‘bacon’, ’eggs’, [’toast’, ‘jam’]] close

   Check   Show Solution