Solutions generators exercises

ex1: Python Students

# python_students.py

class PythonStudents:
    
    def __init__(self):
        self._students = []
        self._populate_students()

    def __iter__(self):
        self.index = 0
        return self

    def __next__(self):
        ri = self.index
        self.index += 1
        if self.index > len(self._students):
            raise StopIteration()
        return self._students[ri]
    
    def _populate_students(self):
        names = ["Claus", "Anna", "Ben", "Diana", "Erik", "Fiona", "George", "Hannah", "Ivan", "Julia"]
        numbers = [1234, 5678, 9101, 1121, 3141, 5161, 7181, 9202, 1222, 3242]

        for i in range(10):
            self._students.append(Student(names[i], numbers[i]))





class Student:

    def __init__(self, name, cpr):
        self.name = name
        self.cpr = cpr

    @property
    def name(self):
            return self.__name

    @name.setter
    def name(self, name):
            self.__name = name.capitalize()

    def __add__(self, student):
            return Student('Anna the daugther', 1234)

    def __str__(self):
            return f'{self.name}, {self.cpr}'

    def __repr__(self):
            return f'{self.__dict__}'

ex2: School of students

# school_of_students.py

import random
import time

def timer(func):
    def wrapper(*args):
        start = time.time()
        val = func(*args)
        end = (time.time()) - start
        print(f'Time elepsed: {end}')
        return val
    return wrapper

names = ['John', 'Corey', 'Adam', 'Steve', 'Rick', 'Thomas']
majors = ['Math', 'Engineering', 'CompSci', 'Arts', 'Business']

@timer
def people_list(num_people):
    result = []
    for i in range(num_people):
        person = {
            'id': i,
            'name': random.choice(names),
            'major': random.choice(majors)
        }
        result.append(person)
    # return result

@timer
def people_generator(num_people):
    for i in range(num_people):
        person = {
            'id': i,
            'name': random.choice(names),
            'major': random.choice(majors)
        }
        yield person

ex3: Range Mimic

# range_mimic.py

# 1. Create a "clone" of the build in range() function.

class range:

    def __init__(self, *args):
        if len(args) == 1:
            self._start = 0
            self._end = args[0]
            self._step = 1
        elif len(args) == 2:
            self._start = args[0]
            self._end = args[1]
            self._step = 1
        elif len(args) == 3:
            self._start = args[0]
            self._end = args[1]
            self._step = args[2]

    def __iter__(self):
        self._i = self._start
        return self

    def __next__(self):
        try:
            if self._end > self._i:
                self._tmp = self._i
                self._i += self._step
                return self._tmp
            else:
                raise StopIteration
        except AttributeError:
            raise TypeError('range method is not itterable')


x = range(2, 12, 2)
for i in x:
    print(i)

# or just:
for i in range(2, 12, 2):
    print(i)

# 2. Now do the same, but use a generator function instead.
def range(*args):
    
    if len(args) == 1:
        start = 0
        end = args[0]
        step = 1
    elif len(args) == 2:
        start = args[0]
        end = args[1]
        step = 1
    elif len(args) == 3:
        start = args[0]
        end = args[1]
        step = args[2]
    
    count = start 
    while count < end:
        yield count
        count += step