4_Dod

4. Dod

Ex00

• *args variable length argument list.
• **kwargs variable length keyword argument list.

Statistics

Statistic	Explanation	Example Use Case	Calculation
Mean	The arithmetic average of a set of numbers.	Calculating the average score in a class.	Add up all numbers and divide by the count of numbers.
Median	The middle value in a sorted list of numbers.	Finding the median income in a dataset.	Arrange numbers in ascending order and find the middle value. If even, average the two middle values.
Quartile	Values that divide a dataset into four equal parts.	Analyzing income distribution in a population.	Sort data, then find the median of the lower half (Q1), median (Q2), and median of the upper half (Q3).
Variance	A measure of how spread out the numbers are.	Assessing the variability of stock returns.	Find the average of squared differences between each number and the mean.
Standard deviation	The square root of the variance.	Understanding the volatility of a portfolio.	Calculate the square root of the variance.

Ex01

A function can return a function. :D

• nonlocal allows to use a variable of an outer scope.
• callable(function) allows to check if function is a function.

Ex02

Creating a decorator.

It needs 3 function levels if decorator has argument @callLimit(3), 2 if not.

• 1st level: decorator args.
• 2nd level: function to execute.
• 3rd level: args for function to execute.

def callLimit(limit: int):
    count = 0
    def callLimiter(function):
        def limit_function(*args: any, **kwds: any):

            try:
                nonlocal count
                count += 1
                return function(*args, **kwds)

        return limit_function

    return callLimiter

Ex03

dataclass usage.

• @dataclass decorator in the class.
• Each attribute is a field. It has different possible arguments:
  • init (True / False): Allows user to give value or not.
  • default: Sets the default value for the field.
  • default_factory: Allows to call a factory function to generate the value.
• __post_init__ can be used to do things after class initialization.

import random
import string
from dataclasses import dataclass, field

def generate_id() -> str:
    return "".join(random.choices(string.ascii_lowercase, k=15))

@dataclass
class Student:
    name: str = field(init=True)
    surname: str = field(init=True)
    active: bool = field(init=False, default=True)
    login: str = field(init=False, default="")
    id: str = field(init=False, default_factory=generate_id)

    def __post_init__(self):
        self.login = self.name[0].upper() + self.surname.lower()