completed prep exercises

Author: TzeMingHo

prep-exercises/__pycache__/dataclasses.cpython-312.pyc

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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
+
+
+def is_adult(person: Person) -> bool:
+    return person.age >= 18
+
+
+imran = Person("Imran", 22, "Ubuntu")
+print(imran.name)
+# print(imran.address)
+# Person doesn't have address attribute
+
+eliza = Person("Eliza", 34, "Arch Linux")
+print(eliza.name)
+# print(eliza.address)
+# Person doesn't have address attribute
+
+# def favorite_song(person: Person) -> str:
+#     return person.song
+# error because person doesn't have song attribute

prep-exercises/classes_and_objects.py

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+from dataclasses import dataclass 
+import datetime as dt
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: dt.date
+    preferred_operating_system: str
+
+    def is_adult(self) -> bool:
+        today = dt.datetime.today()
+
+        age_in_year = today.year - self.age.year
+
+        if (today.month, today.day) < (self.age.month, self.age.day):
+            age_in_year -= 1
+        return age_in_year >= 18
+
+imran = Person("Imran", dt.date.fromisoformat("2002-08-05"), "Ubuntu")
+print(imran)  
+
+imran2 = Person("Imran", dt.date.fromisoformat("2002-08-05"), "Ubuntu")
+print(imran == imran2) 
+
+print(f'{imran.name} is adult: {imran.is_adult()}')

prep-exercises/dataclasses_exercise.py

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+from dataclasses import dataclass
+from enum import Enum
+from typing import List, Dict
+import sys
+
+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
+
+
+def find_possible_laptops(laptops: List[Laptop], person: Person) -> List[Laptop]:
+    possible_laptops = []
+    for laptop in laptops:
+        if laptop.operating_system == person.preferred_operating_system:
+            possible_laptops.append(laptop)
+    return possible_laptops
+
+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 user_register() -> Person:
+
+    user_name: str = input("Please enter your name: ")
+    user_age_str: str = input("Please enter your age: ")
+
+    try:
+        user_age: int = int(user_age_str)
+        if user_age < 0:
+            raise ValueError
+    except ValueError:
+        sys.stderr.write(f'Error: "{user_age_str}" is not a valid age. \n')
+        sys.exit(1)
+
+    user_system_str = input("Please enter your preferred operating system - Arch Linux, Ubuntu, or macOS: ")
+
+    try:
+        user_system = OperatingSystem(user_system_str)
+    except ValueError:
+        sys.stderr.write(f'Error: "{user_system_str}" is not a valid system. \n')
+        sys.exit(1)
+
+    return Person(name=user_name, age=user_age, preferred_operating_system=user_system)
+
+
+def matching_laptop(new_user: Person = user_register()) -> None:
+    possible_laptops = find_possible_laptops(laptops=laptops, person=new_user)
+
+    print(f'Library has {len(possible_laptops)} laptops have {new_user.preferred_operating_system.value}')
+
+    system_counts: Dict[OperatingSystem, int] = {}
+    for laptop in laptops:
+        system_counts[laptop.operating_system] = (system_counts.get(laptop.operating_system) or 0 ) + 1
+
+    most_available = max(system_counts, key=lambda name: system_counts[name])
+
+    if system_counts[most_available] > len(possible_laptops):
+        print(f'if you are willing to accept {most_available.value} you are more likely to get a laptop.')
+
+
+matching_laptop()

prep-exercises/enums.py

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+from dataclasses import dataclass
+from typing import List
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    children: List["Person"]
+
+fatma = Person(name="Fatma", age=10, children=[])
+aisha = Person(name="Aisha", age=12, children=[])
+
+imran = Person(name="Imran", age=50, 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/generics.py

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+from typing import List
+
+class Parent:
+    def __init__(self, first_name: str, last_name: str):
+        self.first_name = first_name
+        self.last_name = last_name
+
+    def get_name(self) -> str:
+        return f"{self.first_name} {self.last_name}"
+
+
+class Child(Parent):
+    def __init__(self, first_name: str, last_name: str):
+        super().__init__(first_name, last_name)
+        self.previous_last_names: List[str] = []
+
+    def change_last_name(self, last_name: str) -> None:
+        self.previous_last_names.append(self.last_name)
+        self.last_name = last_name
+
+    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}"
+
+person1 = Child("Elizaveta", "Alekseeva")
+print(person1.get_name())
+print(person1.get_full_name())
+person1.change_last_name("Tyurina")
+print(person1.get_name())
+print(person1.get_full_name())
+
+person2 = Parent("Elizaveta", "Alekseeva")
+print(person2.get_name())
+# print(person2.get_full_name())
+# person2.change_last_name("Tyurina")
+print(person2.get_name())
+# print(person2.get_full_name())
+
+
+# Predictions:
+# person 1 should be able to print both name and full name as Elizaveta Alekseeva
+# and should be able to print both name Elizaveta Tyurina and full name Elizaveta Tyurina (née Alekseeva) after changing last name to Tyurina
+# because it was created in class Child which inherits get_name from class Parent
+# 
+# In contracts, person 2 is able to print name as Elizaveta Alekseeva
+# but shouldn't be able to print full name as it was create in class Parent, which does not have method get_full_name
+# and couldn't be able to change last name to Tyurina, so the name stays the same Elizaveta Alekseeva
+# and it still won't be able to print full name even after the attempt of change last name 

prep-exercises/inheritance.py

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+# Think of the advantages of using methods instead of free functions. Write them down in your notebook.
+# It is object oriented. The same method can be shared between the same class.
+# It is more obvious to understand the purpose of the methods than a free function 
+
+import datetime as dt
+
+class Person:
+    def __init__(self, name: str, date_of_birth: str, preferred_operating_system: str):
+        self.name = name
+        self.date_of_birth = dt.date.fromisoformat(date_of_birth)
+        self.preferred_operating_system = preferred_operating_system
+
+    def is_adult(self) -> bool:
+        today = dt.datetime.today()
+
+        age_in_year = today.year - self.date_of_birth.year
+
+        if (today.month, today.day) < (self.date_of_birth.month, self.date_of_birth.day):
+            age_in_year -= 1
+        return age_in_year >= 18
+
+imran = Person("Imran", "2000-10-20", "Ubuntu")
+print(imran.is_adult())

prep-exercises/methods.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 = 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 = {
+    "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/type_checking_with_mypy.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:
+        for system in person.preferred_operating_systems:
+            if laptop.operating_system == system:
+                possible_laptops.append(laptop)
+    return possible_laptops
+
+
+people = [
+    Person(name="Imran", age=22, preferred_operating_systems=["Ubuntu", "Arch Linux", "macOS", "Windows"]),
+    Person(name="Eliza", age=34, preferred_operating_systems=["Arch Linux", "Ubuntu", "macOS", "Windows"]),
+]
+
+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}")
+
+    system_list = person.preferred_operating_systems
+    preference_sentences: List[str] = ["prefers {} most of all", ", and then {}", ", but will not use {}"]
+    statement: str = f'{person.name} '
+
+    if len(system_list) != 0:
+        for index, system in enumerate(system_list):
+            if index == 0:
+                statement += preference_sentences[index].format(system)
+            elif index == len(system_list) - 1:
+                statement += preference_sentences[-1].format(system)
+            else:
+                statement += preference_sentences[1].format(system)
+    print(statement)

prep-exercises/type_guided_refactorings.py

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+def double(number: float) -> float:
+    return number * 2
+
+print(double(10))
+
+# The code above was not defined with types for the function and variable
+# I should add the types to fix the code
+# Besides the function name did not reflect its return
+# I make the return as number * 2 instead