W5 Tutorial

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  • Functions and Methods
  • Lists and Tuples
  • Loops

Functions vs Methods

Discussion 1

D1: What is a “method”? How do methods differ from functions? How are they the same?

Exercise 1

E1: Evaluate the following method calls given the assignment s = "Computing is FUN!" Think about the input and output of each method. You’re not expected to know all methods for all types: if you haven’t seen some of these before, your best guess based on the name will probably be right!

  1. s.isupper():
  2. s.upper():
  3. s.endswith("FUN!"):
  4. s.count('i'):
  5. s.strip('!'):
  6. s.replace('i', '!'):

Discussion 2: Lists and Tuples

D2: What is the difference between a “list” and a “tuple”?

Discussion 3: Adding and Removing Items in List

D3: How do we add and remove items from a list?

Exercise 2

E2: Evaluate the following given the assignment lst = [2, ("green", "eggs", "ham"), False]

  1. lst[2]:
  2. lst[1][-2]:
  3. lst[1][-2][:3]:
  4. lst.append(5); print(lst):
  5. lst.pop(2); print(lst):

Discussion 4: Iteration

D4: What is “iteration” in programming? Why do we need it?

Discussion 5: Python Loops

D5: What are the two main types of loop in python? How do we write them?

Discussion 6: Loop Variables

D6: What do we mean by the “loop variable” in a for loop?

Discussion 7

D7: What are the differences between the two main types of loops? In which situations are they used?

Exercise 3

E3: What is the output of the following snippets of code containing loops?

i = 2
while i < 8:
    print(f"The square of {i} is {i * i}")
    i = i + 2

for ingredient in ("corn", "pear", "chilli", "fish"):
    if ingredient.startswith('c'):
        print(ingredient, "is delicious!")
    else:
        print(ingredient, "is not!")

i = 0
colours = ("pink", "red", "blue", "gold", "red")
while i < len(colours):
    if colours[i] == "red":
        print("Found red at index", i)
    i += 1

MIN_WORD_LEN = 5
long_words = 0
text = "There once lived a princess"
for word in text.split():
    if len(word) >= MIN_WORD_LEN:
        print(word, "is too long!")
        long_words += 1
print(long_words, "words were too long")

Discussion 8

D8: Is it always possible to convert a while loop into a for loop and vice versa? How do we do it?

Exercise 4

E4: Rewrite the loops in question 3a and 3b converting for loops to while loops and vice versa. (We’ll include answers for c and d for good measure)

i = 2
while i < 8:
    print(f"The square of {i} is {i * i}")
    i = i + 2

for ingredient in ("corn", "pear", "chilli", "fish"):
    if ingredient.startswith('c'):
        print(ingredient, "is delicious!")
    else:
        print(ingredient, "is not!")

Problem 1

P1: Write a function which takes a positive integer input n and prints the thirteen times tables from 1 _ 13 until n _ 13.

Problem 2

P2: Write a function which converts a temperature between degrees Celsius and Fahrenheit. It should take a float, the temperature to convert, and a string, either 'c' or 'f' indicating a conversion from degrees Celsius and Fahrenheit respectively. The formulae for conversion are below.

Problem 3

P3: Write a function which takes a tuple of strings and returns a list containing only the strings which contain at least one exclamation mark or asterisk symbol. words*with*symbols(('hi', 'there!', '***')) should return ['there!', '__*'].