WestMidlands | 26-SDC-Mar | Chioma Okeke | Sprint 5 | prep exercises

prep-exercises/check_with_mypy.py

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+from typing import Dict
+
+def open_account(balances: Dict[str, int], name: str, amount: int) -> None:
+    balances[name] = amount
+
+def sum_balances(accounts: Dict[str, int]) -> int:
+    total: int = 0
+    for name, pence in accounts.items():
+        print(f"{name} had balance {pence}")
+        total += pence
+    return total
+
+def format_pence_as_string(total_pence: int) -> str:
+    if total_pence < 100:
+        return f"{total_pence}p"
+    pounds = int(total_pence / 100)
+    pence = total_pence % 100
+    return f"£{pounds}.{pence:02d}"
+
+balances: Dict[str, int] = {
+    "Sima": 700,
+    "Linn": 545,
+    "Georg": 831,
+}
+
+open_account(balances, "Tobi", 913)
+open_account(balances, "Olya", 713)
+
+total_pence = sum_balances(balances)
+total_string = format_pence_as_string(total_pence)
+
+print(f"The bank accounts total {total_string}")

prep-exercises/double.py

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+def double(value):
+    return value * 2
+
+# Prediction - Since a string was passed as parameter, it will concatenate twice rather than multiply the number.
+
+print(double("22"))
+
+def double_number(value):
+    return value * 3 
+# The bug is multiplying by 3 rather than 2 as the function name implies. 
+# To fix this, simply return value * 2
+
+print(double_number(10))

prep-exercises/enums.py

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+from dataclasses import dataclass
+from enum import Enum
+from typing import List
+
+class OperatingSystem(Enum):
+    MACOS = "macOS"
+    ARCH = "Arch Linux"
+    UBUNTU = "Ubuntu"
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_system: OperatingSystem
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: OperatingSystem
+
+laptops = [
+    Laptop(id=1, manufacturer="Dell", model="XPS", screen_size_in_inches=13, operating_system=OperatingSystem.ARCH),
+    Laptop(id=2, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system=OperatingSystem.UBUNTU),
+    Laptop(id=3, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system=OperatingSystem.UBUNTU),
+    Laptop(id=4, manufacturer="Apple", model="macBook", screen_size_in_inches=13, operating_system=OperatingSystem.MACOS),
+]
+
+def count_laptops(laptops: List[Laptop], operating_system: OperatingSystem) -> int:
+    count = 0
+    for laptop in laptops:
+        if laptop.operating_system == operating_system:
+            count += 1
+    return count
+
+def most_available_os(laptops: List[Laptop]) -> OperatingSystem:
+    best_os = OperatingSystem.UBUNTU
+    best_count = count_laptops(laptops, best_os)
+
+    for os in OperatingSystem:
+        current_count = count_laptops(laptops, os)
+        if current_count > best_count:
+            best_count = current_count
+            best_os = os
+
+    return best_os
+
+name = input("Enter your name: ")
+age = int(input("Enter your age: "))
+os_input = input("Enter preferred OS (macOS, Arch Linux, Ubuntu):  ")
+
+try:
+    preferred_os = OperatingSystem(os_input)
+except ValueError:
+    print("Invalid operating system.")
+    exit()
+
+person = Person(name, age, preferred_os)
+
+available = count_laptops(laptops, person.preferred_operating_system)
+
+print(
+    f"\nThere are {available} {person.preferred_operating_system.value} laptop(s) available."
+)
+
+best_os = most_available_os(laptops)
+
+if best_os != person.preferred_operating_system:
+    print(
+        f"If you're willing to accept {best_os.value}, you're more likely to get a laptop."
+    )

prep-exercises/inheritance.py

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+class Parent:
+    # Initialise the class
+    def __init__(self, first_name: str, last_name: str):
+        self.first_name = first_name
+        self.last_name = last_name
+
+# Gets first_name and last_name from Parent class
+    def get_name(self) -> str:
+        return f"{self.first_name} {self.last_name}"
+
+
+class Child(Parent):
+    # setup Child class from the superclass Parent
+    # has a new field for previous last names
+    def __init__(self, first_name: str, last_name: str):
+        super().__init__(first_name, last_name)
+        self.previous_last_names = []
+
+# changes the previous lastname to a new provided lastname and adds the prev lastname to a list
+    def change_last_name(self, last_name) -> None:
+        self.previous_last_names.append(self.last_name)
+        self.last_name = last_name
+
+# creates a suffix and appends to fullname if the prev lastname List is not empty
+    def get_full_name(self) -> str:
+        suffix = ""
+        if len(self.previous_last_names) > 0:
+            suffix = f" (née {self.previous_last_names[0]})"
+        return f"{self.first_name} {self.last_name}{suffix}"
+
+# creates an instance of Child class which inherits from Parent class
+person1 = Child("Elizaveta", "Alekseeva")
+print(person1.get_name()) # Elizaveta Alekseeva
+print(person1.get_full_name()) # Elizaveta Alekseeva
+# Changes the lastname to "Tyurina" and append Alekseeva to the previous_last_name List
+person1.change_last_name("Tyurina") 
+print(person1.get_name()) # Elizaveta Tyurina
+print(person1.get_full_name()) # Elizaveta Tyurina (née Alekseeva)
+
+# creates an instance of Parent class
+person2 = Parent("Elizaveta", "Alekseeva")
+print(person2.get_name()) # Elizaveta Alekseeva
+print(person2.get_full_name()) # Error: Parent class does not have the get_full_name() method/attribute and program crashes
+person2.change_last_name("Tyurina") # Error: Parent class does not have the change_last_name() method, program crash
+print(person2.get_name()) # Elizaveta Alekseeva
+print(person2.get_full_name()) # Error: Parent class does not have the get_full_name() method/attribute, program crash

prep-exercises/person_class.py

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+class Person:
+    def __init__(self, name: str, age: int, preferred_operating_system: str):
+        self.name = name
+        self.age = age
+        self.preferred_operating_system = preferred_operating_system
+
+imran = Person("Imran", 22, "Ubuntu")
+print(imran.name)
+# print(imran.address) - Person class has no address attribute, hence the error message in mypy on lines 9 and 13
+
+eliza = Person("Eliza", 34, "Arch Linux")
+print(eliza.name)
+# print(eliza.address) - same as line 9
+
+def is_adult(person: Person) -> bool:
+    return person.age >= 18
+
+print(is_adult(imran))
+
+# This function will generate an attribute error when mypy runs it, because gender is not an attribute of the class, Person.
+def check_gender(person: Person) -> str:
+    return person.gender

prep-exercises/person_dataclass.py

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+from datetime import date
+from dataclasses import dataclass
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    date_of_birth: date
+    preferred_operating_system: str
+
+    def is_adult(self) -> bool:
+        today = date.today()
+
+        age = today.year - self.date_of_birth.year
+
+        if (today.month, today.day) < (self.date_of_birth.month, self.date_of_birth.day):
+            age -= 1
+
+        return age >= 18
+
+imran = Person("Imran", date(2000, 10, 11), "Ubuntu")
+print(imran)
+print(imran.is_adult())

prep-exercises/person_generics.py

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+from dataclasses import dataclass
+from typing import List
+# from datetime import date
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    children: List["Person"]
+
+fatma = Person(name="Fatma", age=10, children=[])
+aisha = Person(name="Aisha", age=7, children=[])
+
+imran = Person(name="Imran", age=38, children=[fatma, aisha])
+
+def print_family_tree(person: Person) -> None:
+    print(person.name)
+    for child in person.children:
+        print(f"- {child.name} ({child.age})")
+
+print_family_tree(imran)

prep-exercises/person_method.py

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+import datetime as dt
+
+class Person:
+    def __init__(self, name: str, dob: dt.date, preferred_operating_system: str):
+        self.name = name
+        self.dob = dob
+        self.preferred_operating_system = preferred_operating_system
+
+    def is_adult(self) -> bool:
+        today = dt.date.today()
+
+        age = today.year - self.dob.year
+
+        if (today.month, today.day) < (self.dob.month, self.dob.day):
+            age -= 1
+
+        return age >= 18
+
+imran = Person("Imran", dt.date(1998, 11, 13), "Ubuntu")
+print(imran.is_adult())

prep-exercises/type_refactoring.py

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+from dataclasses import dataclass
+from typing import List
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_systems: List[str]
+
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: str
+
+
+def find_possible_laptops(laptops: List[Laptop], person: Person) -> List[Laptop]:
+    possible_laptops = []
+    for laptop in laptops:
+        if laptop.operating_system == person.preferred_operating_systems[0]:
+            possible_laptops.append(laptop)
+    return possible_laptops
+
+
+people = [
+    Person(name="Imran", age=22, preferred_operating_systems=["Ubuntu", "Arch Linux"]),
+    Person(name="Eliza", age=34, preferred_operating_systems=["Arch Linux", "macOS"]),
+]
+
+laptops = [
+    Laptop(id=1, manufacturer="Dell", model="XPS", screen_size_in_inches=13, operating_system="Arch Linux"),
+    Laptop(id=2, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system="Ubuntu"),
+    Laptop(id=3, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system="ubuntu"),
+    Laptop(id=4, manufacturer="Apple", model="macBook", screen_size_in_inches=13, operating_system="macOS"),
+]
+
+for person in people:
+    possible_laptops = find_possible_laptops(laptops, person)
+    print(f"Possible laptops for {person.name}: {possible_laptops}")