Learn Encapsulation by Building a Projectile Trajectory Calculator - Step 13

Python
1

Tell us what’s happening:

I’m missing something here… It seems the way my string is formated is wrong, i don’t understan though. What are the requisites that my formated string should have? I played around it for a while now but it does not seem that any of the ways in which I formated the string is good… Thanks in advance!
The problem seems to be here:

def __repr__(self):
        return f"{self.__class__.__name__} = {self.__coordinates})"

Your code so far

import math

GRAVITATIONAL_ACCELERATION = 9.81
PROJECTILE = "∙"
x_axis_tick = "T"
y_axis_tick = "⊣"

class Projectile:
    __slots__ = ('__speed', '__height', '__angle')

    def __init__(self, speed, height, angle):
        self.__speed = speed
        self.__height = height
        self.__angle = math.radians(angle)
        
    def __str__(self):
        return f'''
Projectile details:
speed: {self.speed} m/s
height: {self.height} m
angle: {self.angle}°
displacement: {round(self.__calculate_displacement(), 1)} m
'''

    def __calculate_displacement(self):
        horizontal_component = self.__speed * math.cos(self.__angle)
        vertical_component = self.__speed * math.sin(self.__angle)
        squared_component = vertical_component**2
        gh_component = 2 * GRAVITATIONAL_ACCELERATION * self.__height
        sqrt_component = math.sqrt(squared_component + gh_component)
        
        return horizontal_component * (vertical_component + sqrt_component) / GRAVITATIONAL_ACCELERATION
        
    def __calculate_y_coordinate(self, x):
        height_component = self.__height
        angle_component = math.tan(self.__angle) * x
        acceleration_component = GRAVITATIONAL_ACCELERATION * x ** 2 / (
                2 * self.__speed ** 2 * math.cos(self.__angle) ** 2)
        y_coordinate = height_component + angle_component - acceleration_component

        return y_coordinate
    
    def calculate_all_coordinates(self):
        return [
            (x, self.__calculate_y_coordinate(x))
            for x in range(math.ceil(self.__calculate_displacement()))
        ]

    @property
    def height(self):
        return self.__height

    @property
    def angle(self):
        return round(math.degrees(self.__angle))

    @property
    def speed(self):
        return self.__speed

    @height.setter
    def height(self, n):
        self.__height = n

    @angle.setter
    def angle(self, n):
        self.__angle = math.radians(n)

    @speed.setter
    def speed(self, s):
       self.__speed = s

    def __repr__(self):
        return f"{self.__class__.__name__}({self.speed}, {self.height}, {self.angle})"


# User Editable Region

class Graph:
    __slots__ = ('__coordinates')  

    def __init__(self, coordinates):
        self.__coordinates = coordinates  

    def __repr__(self):
        return f"{self.__class__.__name__} = {self.__coordinates})"  

ball = Projectile(10, 3, 45)
print(ball)
coordinates = ball.calculate_all_coordinates()
graph = Graph(coordinates) 
print(graph)



# User Editable Region

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Challenge Information:

Learn Encapsulation by Building a Projectile Trajectory Calculator - Step 13

2

the string needs to give something like this (but where the coordinates are spelled out). You should not have an assignment in the repr string

1 Like
3

Solved! Thanks for the help, now I fully understood the concept. I overthinked on that but in the end, now the concept of how repr should work is very clear, again, thanks!

4

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