London| 26-Jul-SDC | Shaghayegh far| Sprint 5 | Prep Exercises

Sprint-5/ExerSice10.py

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+
+#enum exersice
+
+from dataclasses import dataclass
+from typing import List
+import sys
+
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_system: str
+
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: str
+
+
+laptops = [
+    Laptop(1, "Dell", "XPS", 13, "Ubuntu"),
+    Laptop(2, "Dell", "XPS", 15, "Ubuntu"),
+    Laptop(3, "Dell", "XPS", 15, "Arch Linux"),
+    Laptop(4, "Apple", "MacBook", 13, "macOS"),
+    Laptop(5, "Lenovo", "ThinkPad", 14, "Ubuntu"),
+]
+
+
+name = input("Enter your name: ")
+
+try:
+    age = int(input("Enter your age: "))
+except ValueError:
+    print("Error: age must be a number.", file=sys.stderr)
+    sys.exit(1)
+
+
+preferred_operating_system = input(
+    "Enter your preferred operating system: "
+)
+
+available_operating_systems = {
+    laptop.operating_system for laptop in laptops
+}
+
+if preferred_operating_system not in available_operating_systems:
+    print(
+        "Error: that operating system is not available.",
+        file=sys.stderr
+    )
+    sys.exit(1)
+
+
+person = Person(
+    name=name,
+    age=age,
+    preferred_operating_system=preferred_operating_system
+)
+
+
+matching_laptops = [
+    laptop
+    for laptop in laptops
+    if laptop.operating_system == person.preferred_operating_system
+]
+
+print(
+    f"The library has {len(matching_laptops)} "
+    f"laptop(s) with {person.preferred_operating_system}."
+)
+
+
+laptop_counts = {}
+
+for laptop in laptops:
+    laptop_counts[laptop.operating_system] = (
+        laptop_counts.get(laptop.operating_system, 0) + 1
+    )
+
+
+for operating_system, count in laptop_counts.items():
+    if (
+        operating_system != person.preferred_operating_system
+        and count > len(matching_laptops)
+    ):
+        print(
+            f"The library has more {operating_system} laptops "
+            f"({count}). You are more likely to get a laptop "
+            f"if you are willing to use {operating_system}."
+        )

Sprint-5/Exersice1.py

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+
+# 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?
+
+
+# double("22") returns "2222".
+
+# "22" is a string, so * 2 repeats the string twice.
+
+
+def half(value):
+return value / 2
+
+def double(value):
+return value * 2
+
+def second(value):
+return value[1]
+
+print(double(22))
+print(double("hello"))
+print(double("22"))
+
+print(second(22))
+print(second(0x16))
+print(second("hello"))
+print(second("22"))
+

Sprint-5/Exersice11.py

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+# Inheritance exercise.
+
+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())
+
+# Parent does not have get_full_name()
+# print(person2.get_full_name())
+
+# Parent does not have change_last_name()
+# person2.change_last_name("Tyurina")
+
+# These would work if the above line was not an error:
+# print(person2.get_name())
+# print(person2.get_full_name())

Sprint-5/Exersice2.py

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+
+# Read the above code and write down what the bug is. How would you fix it?
+
+# The bug was that the function multiplied the number by 3.
+
+# Since the function is called double, it should multiply the number by 2.
+
+def double(number):
+return number * 2
+
+print(double(10))
+
+

Sprint-5/Exersice3.py

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+# type checking
+
+rom 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}")
+
+# Answer:
+
+# The type annotations tell mypy what types are expected.
+
+# balances contains string names and integer balances.
+
+# The account amounts are stored as pence, so £9.13 is 913
+
+# and £7.13 is 713.
+
+# format_pence_as_string returns a string.
+
+# The original function call had the wrong function name:
+
+# format_pence_as_str -> format_pence_as_string

Sprint-5/Exersice4.py

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+# Classes and objects
+
+# Classes and objects
+
+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)
+
+
+def is_adult(person: Person) -> bool:
+    return person.age >= 18
+
+
+print(is_adult(imran))
+
+
+
+
+def is_developer(person: Person) -> bool:
+    return person.is_developer
+
+
+print(is_developer(imran))
+
+# there is an error because the is_developer attribute is not  in the Person class.

Sprint-5/Exersice5.py

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+# methods 
+
+# Think of the advantages of using methods
+
+Encapsulation: 
+Data and methods are kept together in one class, which controls how the data can be accessed or changed. It hides the implementation details and allows the implementation to change without affecting the user, as long as the interface stays the same. 
+For example, a Person class can control how a person's data is modified.
+
+
+Ease of use: 
+Users only need to know how to use the class's interface, not how it works internally. Methods can be easily accessed using dot notation and IDE autocomplete, 
+for example person.is_adult().

Sprint-5/Exersice6.py

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+
+# 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.
+
+import datetime as dt
+
+class Person:
+    def __init__(self, name: str, birthdate: dt.date, preferred_operating_system: str):
+        self.name = name
+        self.birthdate = birthdate
+        self.preferred_operating_system = preferred_operating_system
+        self.birthdate = birthdate
+
+    def is_adult(self) -> bool:
+        today = dt.date.today()
+        print(today)
+        return today >= dt.date(self.birthdate.year +18, self.birthdate.month, self.birthdate.day)
+
+   imran = Person("Imran", dt.date(2008,8,6), "Ubuntu")
+   print(imran.is_adult())

Sprint-5/Exersice7.py

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+
+# Write a Person class using @datatype which uses a datetime.date for date of birth, rather than an int for age.
+
+from dataclasses import dataclass
+from datetime import date
+
+
+@dataclass
+class Person:
+    name: str
+    date_of_birth: date
+    preferred_operating_system: str
+
+    def is_adult(self) -> bool:
+        today = date.today()
+
+        years = today.year - self.date_of_birth.year
+
+        had_birthday_this_year = (
+            (today.month, today.day)
+            >= (self.date_of_birth.month, self.date_of_birth.day)
+        )
+
+        age = years if had_birthday_this_year else years - 1
+
+        return age >= 18
+
+
+imran = Person(
+    "Imran",
+    date(2008, 8, 6),
+    "Ubuntu"
+)
+
+print(imran.is_adult())

Sprint-5/Exersice8.py

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+# Generic exersice
+
+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=5, children=[])
+aisha = Person(name="Aisha", age=8, 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)