Learn Encapsulation by Building a Projectile Trajectory Calculator - Step 14

Python
1

Tell us what’s happening:

I have added debug code to try to figure out why this step doesn’t pass. As you can see the number of characters between what I output and the example are the same, and I test that the output and the example are the same, and they match. What am I missing.

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__}({self.speed}, {self.height}, {self.angle})'

class Graph:
    __slots__ = ('__coordinates')

    def __init__(self, coord):
        self.__coordinates = coord
    
    def __repr__(self):
        return f'Graph({self.__coordinates})'


# User Editable Region

    def create_coordinates_table(self):
        s = f'\n{"x":>3}{"y":>7}\n'

        for x, y in self.__coordinates:
            s += f'{x:>3}{y:>7.2f}\n'
        print(s)
        example = """
  x      y
  0   3.00
  1   3.90
  2   4.61
  3   5.12
  4   5.43
  5   5.55
  6   5.47
  7   5.19
  8   4.72
  9   4.05
 10   3.19
 11   2.13
 12   0.87
"""
        print(f'len(s): {len(s)}')
        print(f'len(example): {len(example)}')
        print(f'(Does s == example: {s == example}')


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

graph = Graph(coordinates)
graph.create_coordinates_table()


# User Editable Region

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Challenge Information:

Learn Encapsulation by Building a Projectile Trajectory Calculator - Step 14

2

run the tests with the browser console open and you should see a AssertionError: print(graph.create_coordiantes_table()) is missing, but that’s the second test failing.

For the first one, what is the function returning?

3

D’Oh! I was printing in the wrong place.