Learn Interfaces by Building an Equation Solver - Step 25

Python
1

Tell us what’s happening:

im stuck im confused, what does it mean then declare a variable x and assign it the solution.

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")
        self.coefficients = {(len(args) - n - 1): arg for n, arg in enumerate(args)}

    def __init_subclass__(cls):
        if not hasattr(cls, "degree"):
            raise AttributeError(
                f"Cannot create '{cls.__name__}' class: missing required attribute 'degree'"
            )

    def __str__(self):
        terms = []
        for n, coefficient in self.coefficients.items():
            if not coefficient:
                continue
            if n == 0:
                terms.append(f'{coefficient:+}')
            elif n == 1:
                terms.append(f'{coefficient:+}x')                
        equation_string = ' '.join(terms) + ' = 0'
        return equation_string.strip('+').strip('+')        
    
    @abstractmethod
    def solve(self):
        pass
        
    @abstractmethod
    def analyze(self):
        pass
        
class LinearEquation(Equation):
    degree = 1

# User Editable Region

    def solve(self):
        self.coefficients= x
        self.coefficients.values(a,b) 
        return solve()

# User Editable Region

    
    def analyze(self):
        pass
    
lin_eq = LinearEquation(2, 3)
print(lin_eq)

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Challenge Information:

Learn Interfaces by Building an Equation Solver - Step 25

2

also why doesn’t it keep it to the style of my code? why does it change it to what it wants, it just makes it more confusing for me cuz i don’t understand the len(args) - n - 1): arg for n, arg in enumerate(args)}

3

now i have got

self.coefficients.values(a,b)
        x = -b/a
4
  • If you want to unpack the coefficients stored in the coefficients attribute into the variables a and b, do not put a and b within parentheses of the ‘.values()’ but assign the whole line (without a and b) you already have to variables a and b like this:
a, b = ...
  • After the second line, return x.
5

wait you can do that… it worked ! you have very good explanations

1 Like