London | 25-SDC-July | Mikiyas Gebremichael | Sprint 4 | Prep exercises

prep_exercises/exercise1.py

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+def double(value):
+    return value * 2
+
+print(double("22"))
+#Predict what double("22") will do
+
+#Answer
+#"2222" because "22" will be treated as a string and then the program just duplicates it and return 2222 with a string value
+
+def double(number):
+    return number * 3
+
+print(double(10))
+
+#find the bug
+#answer
+#This is a logic error instead of giving the double it returns the triple of the number 
+#we can improve it by changing 3 by 2 since it doesnt have any type error

prep_exercises/exercise2typeannotation.py

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+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 = 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/exercise3.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)
+
+eliza = Person("Eliza", 34, "Arch Linux")
+print(eliza.name)
+print(eliza.address)
+
+#imran.address and eliza.address is not valid attribute
+#error: "Person" has no attribute "address"
+
+
+def is_adult(person: Person) -> bool:
+    return person.age >= 18
+
+print(is_adult(imran))
+#ok
+
+def get_city(person: Person) -> str:
+    return person.city
+#person has no attribute city.
+
+#to run mypy   mypy ./***.py

prep_exercises/exercise4.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
+
+    def is_adult(self):
+        return self.age >= 18
+
+imran = Person("Imran", 22, "Ubuntu")
+print(imran.is_adult())
+
+#✍️exercise
+#Think of the advantages of using methods instead of free functions. Write them down in your notebook.
+
+
+#answer
+#Reusability
+#Polymorphism – Different subclasses can override the same method name with different behaviour.
+
+
+#exercise
+#Change the Person class to take a date of birth (using the standard library’s datetime.date class) and store it in a field instead of age.
+from datetime import date
+class Person:
+    def __init__(self, name: str, date_of_birth: date, preferred_operating_system: str):
+        self.name = name
+        self.date_of_birth = date_of_birth
+        self.preferred_operating_system = preferred_operating_system
+
+    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
+#example 
+imra = Person("Imra", date(2003, 7, 14), "Ubuntu")
+eliz = Person("Eliz", date(1991, 3, 25), "Arch Linux")
+
+print(imra.is_adult())  
+print(eliz.is_adult())  

prep_exercises/exercise5.py

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+from dataclasses import dataclass
+from datetime import date
+
+@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): #if bd havent occured even once this year -1
+            age -= 1
+        return age >= 18
+
+#example
+imran = Person("Imran", date(2003, 7, 14), "Ubuntu")
+eliza = Person("Eliza", date(1991, 3, 25), "Arch Linux")
+print(imran)
+print(imran.is_adult())
+print(eliza.is_adult())

prep_exercises/exercise6.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=8, children=[])
+aisha = Person(name="Aisha", age=6, children=[])
+
+imran = Person(name="Imran", age=35, 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/exercise7.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]:
+    # create a set of lowercase preferred names for faster membership checks
+    prefs_lower = {os.lower() for os in person.preferred_operating_systems} #turn the string in to lowercase and it stores is on our set called prefs_lower
+    possible_laptops: List[Laptop] = []
+    for laptop in laptops:
+        if laptop.operating_system.lower() in prefs_lower:
+            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"]),
+]
+
+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}")
+# now ubuntu and Ubuntu is the same match
+# by basically checking if the lower case version of our text is there we declare it is the same thing 

prep_exercises/exercise8laptopallocation.py

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+from dataclasses import dataclass
+from enum import Enum
+from typing import List
+from collections import Counter
+import sys
+
+class OperatingSystem(Enum):
+    MACOS = "macOS"
+    ARCH = "Arch Linux"
+    UBUNTU = "Ubuntu"
+
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: OperatingSystem
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_system: OperatingSystem
+
+#library’s laptops
+laptops = [
+    Laptop(1, "Dell", "XPS 13", 13, OperatingSystem.ARCH),
+    Laptop(2, "Dell", "XPS 15", 15, OperatingSystem.UBUNTU),
+    Laptop(3, "Lenovo", "ThinkPad", 14, OperatingSystem.UBUNTU),
+    Laptop(4, "Apple", "MacBook Air", 13, OperatingSystem.MACOS),
+]
+#user input
+name = input("Enter your name: ").strip()
+try:
+    age = int(input("Enter your age: ").strip())
+except ValueError:
+    print("Error Age must be a number ", file=sys.stderr)
+    sys.exit(1)
+os_input = input("Enter your preferred operating system (macOS / Arch Linux / Ubuntu): ").strip()
+try:
+    preferred_os = OperatingSystem(os_input)
+except ValueError:
+    print(f"Error '{os_input}' is not a valid operating system.", file=sys.stderr)
+    print("Valid options are:", [os.value for os in OperatingSystem], file=sys.stderr)
+    sys.exit(1)
+
+#Processing
+person = Person(name=name, age=age, preferred_operating_system=preferred_os)
+matching_laptops = [l for l in laptops if l.operating_system == person.preferred_operating_system]
+
+print(f"\n library has {len(matching_laptops)} laptop/s with {preferred_os.value}")
+
+#suggest an alternative if better availability
+os_counts = Counter([l.operating_system for l in laptops])
+most_common_os, most_common_count = os_counts.most_common(1)[0]
+
+if most_common_os != preferred_os and most_common_count > len(matching_laptops):
+    print(f"💡 There are more laptops with {most_common_os.value}.")
+    print(f"If you’re willing to use {most_common_os.value}, you’re more likely to get one.")

prep_exercises/exercise9inheritance.py

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+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 = []
+
+    def change_last_name(self, last_name) -> 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())
+
+
+#without commenting the three lines the output was like thiss  
+#Elizaveta Alekseeva
+#Elizaveta Alekseeva
+#Elizaveta Tyurina
+#Elizaveta Alekseeva
+#Elizaveta Tyurina (née Alekseeva)
+#Traceback (most recent call last):
+#  File "/Users/Module-Decomposition/prep_exercises/exercise9inheritance.py", line 34, in <module>
+#    print(person2.get_full_name())
+#AttributeError: 'Parent' object has no attribute 'get_full_name'