London | 26-SDC-Mar | Mariia Serhiienko | Sprint 5 |Prep exercises

.gitignore

@@ -1,2 +1,5 @@
 node_modules
 testoutput.txt
+.venv
+__pycache__
+.mypy_cache

sprint-5-prep/1-use-types.py

@@ -0,0 +1,50 @@
+# Exercise-1
+
+# Predict what double("22") will do. 
+# Then run the code and check. Did it do what you expected? 
+# Why did it return the value it did?
+
+def double(value):
+    return value * 2
+
+#Answer
+#I guess it'll return 2222. That's because any value in quotes is a string, 
+# and when strings are multiplied, they repeat the characters.
+
+def double(value):
+    return value * 2
+
+print("double is:", double("22"))   #double is: 2222
+
+# Yes, It returned 2222 as I predicted.
+# Python's operator "*" when used with a string and a number, repeats this string as "number" times,
+# and it didn't convert the string "22" into number 22.
+
+
+#Exercise-2
+
+def double(number):
+    return number * 3
+
+print(double(10))
+
+
+#Read the above code and write down what the bug is. How would you fix it?
+
+# Answer
+# There are two way to fix it:
+# 1. Change *3 to *2.
+
+def double(number):
+    return number * 2
+
+print(double(10))
+
+# or
+
+# 2. Rename the function to "triple" if we want multiply by 3 - it keeps the logic correct.
+
+def triple(number):
+    return number * 3
+
+print(triple(10))

sprint-5-prep/2-type-checking-mypy.py

@@ -0,0 +1,31 @@
+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)
+
+print(f"The bank accounts total {total_string}")

sprint-5-prep/3-classes-and-objects.py

@@ -0,0 +1,24 @@
+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)
+#error: Person class has no attribute "address"
+
+eliza = Person("Eliza", 34, "Arch Linux")
+print(eliza.name)
+#print(eliza.address)
+#the same error: Person class has no attribute "address"
+
+def is_adult(person: Person) -> bool:
+    return person.age >= 18
+
+print(is_adult(imran))
+
+def get_phone(person: Person) -> str:
+    return person.phone_number
+# After running mypy this method also causes an error, because Person class has no attribute "phone_number"

sprint-5-prep/4-methods.py

@@ -0,0 +1,44 @@
+# Exercises-1
+# Think of the advantages of using methods instead of free functions. 
+# Write them down in your notebook.
+
+# 1. Organisation: all Person-related logic lives inside the Person class.
+
+# 2. Encapsulation: we only have to update the method once, 
+# for example if we change "age" to "date_of_birth" inside the class.
+# With free functions, we'd have to update every function that touches person.age across the whole codebase.
+
+# 3. Simple search: if we type "imran." our editor shows everything Person can do.
+# With free functions, we have to remember they exist.
+
+# 4. Clear ownership: "person.is_adult()" is definitely about a person,
+# but with "is_adult(x)" we don't know what it's about.
+
+# 5. Easier to catch errors with mypy, because all methods related to the class are in one place.
+
+
+# Exercises-2
+# 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.
+#
+# Update the is_adult method to act the same as before.
+
+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
+
+imran = Person("Imran", date(2003, 6, 20), "Ubuntu")
+print(imran.is_adult())

sprint-5-prep/5-dataclasses.py

@@ -0,0 +1,22 @@
+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):
+            age -= 1
+        return age >= 18
+
+
+zoi = Person("Zoi", date(2003, 3, 23), "Ubuntu")
+
+print("zoi:", zoi)
+print("zoi.is_adult():", zoi.is_adult())

sprint-5-prep/6-generics.py

@@ -0,0 +1,20 @@
+from dataclasses import dataclass
+from typing import List
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    children: list["Person"]
+    age: int
+
+fatma = Person(name="Fatma", age=9, children=[])
+aisha = Person(name="Aisha", age=5, 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)

sprint-5-prep/7-type-guided-refactorings.py

@@ -0,0 +1,42 @@
+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 in person.preferred_operating_systems:
+            possible_laptops.append(laptop)
+    return possible_laptops
+
+
+people = [
+    Person(name="Imran", age=22, preferred_operating_systems=["Ubuntu"]),
+    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}")

sprint-5-prep/8-enums.py

@@ -0,0 +1,79 @@
+from dataclasses import dataclass
+from enum import Enum
+from typing import List
+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
+
+os_input_name = input("Your name is: ")
+
+os_input_age = input("Your age is: ")
+try:
+    age = int(os_input_age)
+except ValueError:
+    print(f"Error: '{os_input_age}' is not a valid age", file=sys.stderr)
+    sys.exit(1)
+
+os_input_preferred_os = input("Preferred operating system is: ")
+try:
+    preferred_operating_system = OperatingSystem(os_input_preferred_os)
+except ValueError:
+    print(f"Error: '{os_input_preferred_os}' is not a valid operating system", file=sys.stderr)
+    sys.exit(1)
+
+person = Person(name = os_input_name, age=age, preferred_operating_system=preferred_operating_system)
+
+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),
+    Laptop(id=5, manufacturer="Apple", model="macBook", screen_size_in_inches=14, operating_system=OperatingSystem.MACOS),
+    Laptop(id=6, manufacturer="Apple", model="macBook", screen_size_in_inches=15, operating_system=OperatingSystem.MACOS),
+]
+
+def find_specific_os(laptops: List[Laptop], preferred_os: OperatingSystem) -> List[Laptop]:
+    possible_laptops = []
+
+    for laptop in laptops:
+        if (laptop.operating_system == preferred_os):
+            possible_laptops.append(laptop)
+
+    possible_laptops_amount = len(possible_laptops)
+
+    print(f"The amount of possible laptops with preferred operating system is", possible_laptops_amount)
+
+    return possible_laptops
+
+result = find_specific_os(laptops, preferred_operating_system)
+
+counts_laptop_per_os: dict[OperatingSystem, int] = {}
+
+for laptop in laptops:
+    os = laptop.operating_system
+    if os in counts_laptop_per_os:
+        counts_laptop_per_os[os] += 1
+    else:
+        counts_laptop_per_os[os] = 1
+
+top_os = max(counts_laptop_per_os, key=lambda os: counts_laptop_per_os[os])
+
+if top_os != preferred_operating_system:
+    print(f"If you're willing to use {top_os.value}, you're more likely to get a laptop ({counts_laptop_per_os[top_os]} available)")