Learn Interfaces by Building an Equation Solver - Step 17

Python
1

Tell us what’s happening:

I’m trying to make a dictionary with the coefficients of the equation, but I’m stuck. Please help me!
I’ve tried this code self.coefficients = {key: val for (key, val) in enumerate(args)} with and without tuple notation, with str(key) instead of key, and so on.

Your code so far

from abc import ABC, abstractmethod

class Equation(ABC):
    degree: int
    
    def __init__(self, *args):
        if (self.degree + 1) != len(args):
            raise TypeError(
                f"'Equation' object takes {self.degree + 1} positional arguments but {len(args)} were given"
            )
        if any(not isinstance(arg, (int, float)) for arg in args):
            raise TypeError("Coefficients must be of type 'int' or 'float'")
        if args[0] == 0:
            raise ValueError("Highest degree coefficient must be different from zero")

# User Editable Region

        self.coefficients = {key: val for key, val in enumerate(args)}

# User Editable Region

    def __init_subclass__(cls):
        if not hasattr(cls, "degree"):
            raise AttributeError(
                f"Cannot create '{cls.__name__}' class: missing required attribute 'degree'"
            )
    
    @abstractmethod
    def solve(self):
        pass
        
    @abstractmethod
    def analyze(self):
        pass
        
class LinearEquation(Equation):
    degree = 1
    
    def solve(self):
        pass
    
    def analyze(self):
        pass

    
lin_eq = LinearEquation(2, 3)

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Challenge Information:

Learn Interfaces by Building an Equation Solver - Step 17

2

Instructions:

For example, a LinearEquation object instantiated with 2 and 4 should have the following coefficients attribute: {1: 2, 0: 4} , because 2 corresponds to the first degree of x and 4 corresponds to zero-th degree of x .

Let’s check what your code does:
I changed the last line to lin_eq = LinearEquation(2, 4) to match the description

then, I have added print(self.coefficients) right below your code
result: {0: 2, 1: 4}. Your coefficients do not match the requirements.

3

Thank you! Usually I know something about math, but I was a little bit blind there.
I tried with len(args)-key for the dictionary key, but it only works with self.degree-key.

4

for a linear equation, the degree is 1, while len(args) is 2

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