I tried to create a code that calls a class. But I get

TypeError: EulerMethod() takes no arguments

The main code that calls the class is;

import numpy as np
import HW_3_euler as eum

x = input('define independent variable:\t')
y = input('define dependent variable:\t')
h = float(input('define the iteration value:\t'))
range_ = np.asarray(np.linspace(float(input('define the dependent variable range:\t')),float(input()),6))
equation_str = input('define the equation:\t')
locals()[x] = float(input('define x_0 value:\t'))
locals()[y] = float(input('define y value at x=0:\t'))
 
result_ = eum.EulerMethod(x, y, h, equation_str, range_)
print(result_)

and the class is;

class EulerMethod:
    """Euler Method approach"""

#dervf = 3 * x**2 * y - 5.4 * x * y   0.15 * y**2
def __init__(self, chi, ups, dlt, equation_str, range_):
    self.chi = chi
    self.ups = ups
    self.dlt = dlt
    self.range_ = range_
    self.equation_str = equation_str

def func(self):
    i = 0
    results_ = self.range_
    results_[0] = self.ups
    for i in (range(len(self.range_))-1):
        results_[i 1] = self.ups   self.dlt * eval(self.equation_str)
        self.chi = self.range_[i 1]
        self.ups = results_[i 1]
        return EulerMethod()

the purpose of to create this code is to find initial value problem by Euler Method. the main code sends the parameter 'x', 'y', 'delta x (declared as 'h')', equation in string and 'x' values in array. I predict that class return 'y' values in array format.

CodePudding user response：

may not be the problem, but the code as it is pasted has an indentation error that would explain the Exception.

it should be:

class EulerMethod:
    """Euler Method approach"""

    #dervf = 3 * x**2 * y - 5.4 * x * y   0.15 * y**2
    def __init__(self, chi, ups, dlt, equation_str, range_):
        self.chi = chi
        self.ups = ups
        self.dlt = dlt
        self.range_ = range_
        self.equation_str = equation_str

    def func(self):
        i = 0
        results_ = self.range_
        results_[0] = self.ups
        for i in (range(len(self.range_))-1):
            results_[i 1] = self.ups   self.dlt * eval(self.equation_str)
            self.chi = self.range_[i 1]
            self.ups = results_[i 1]
            return EulerMethod()

CodePudding user response：

TypeError: EulerMethod() takes no arguments means the class doesn't have any def __int inside it. Looking at your code, I can see that your def __init__'s indent is wrong. Since your indent is wrong, the whole class can't take any argument.

Change to this should fix your issue.

class EulerMethod:
    """Euler Method approach"""

    #dervf = 3 * x**2 * y - 5.4 * x * y   0.15 * y**2
    def __init__(self, chi, ups, dlt, equation_str, range_):
        self.chi = chi
        self.ups = ups
        self.dlt = dlt
        self.range_ = range_
        self.equation_str = equation_str

    def func(self):
        i = 0
        results_ = self.range_
        results_[0] = self.ups
        for i in (range(len(self.range_))-1):
            results_[i 1] = self.ups   self.dlt * eval(self.equation_str)
            self.chi = self.range_[i 1]
            self.ups = results_[i 1]
            return EulerMethod()