问题
I am trying to learn how to group functions by class. As an example, I tried to code a generalized least squares method to find the equation of a best-fitting line between a set of (x,y) coordinates. For my particular case, I chose a simple line y = x + 5, so slope should be close to 1 and y-intercept should be close to 5. Running my attempt at a coded solution below produces the error TypeError: set_x() takes 1 positional argument but 2 were given, though I am trying to pass an array of x-points. How can I circumvent this error?
import numpy as np
from scipy.optimize import minimize
class GeneralizedLeastSquares:
def __init__(self, residuals=None, parameters=None, x=None, y_true=None, y_fit=None, weights=None, method=None):
self.residuals = residuals
self.parameters = parameters
self.x = x
self.y_true = y_true
self.y_fit = y_fit
self.weights = weights
self.method = method
def set_residuals(self, residuals):
self.residuals = residuals
def set_parameters(self, parameters):
self.parameters = parameters
def set_x(self, x):
self.x = x
def set_y_true(self, y_true):
self.y_true = y_true
def set_y_fit(self, y_fit):
self.y_fit = y_fit
def set_weights(self, weights):
self.weights = weights
def set_method(self, method):
self.method = method
def get_residuals(self):
return [(self.y_true[idx] - self.y_fit[idx])**2 for idx in range(len(self.y_true)) if len(self.y_true) == len(self.y_fit) ]
def get_parameters(self):
return self.parameters
def get_x(self):
return self.x
def get_y_true(self):
return self.y_true
def get_y_fit(self):
return [self.parameters[0] * self.x[idx] + self.parameters[1] for idx in range(len(self.x))]
def get_weights(self):
return self.weights
def update_weights(self):
inverse_residuals = [1/self.residuals[idx] for idx in range(len(residuals))]
inverse_residuals_abs = [abs(inverse_residual) for inverse_residual in inverse_residuals]
residual_abs_total = sum(inverse_residuals_abs)
return [inverse_residuals_abs[idx]/residual_abs_total for idx in range(len(inverse_residuals_abs))]
def get_method(self):
return self.method
def get_error_by_residuals(self):
return sum([self.weights[idx] * self.residuals[idx] for idx in range(len(self.residuals))])
def get_error_by_std_mean(self):
return np.std(self.y_true)/np.sqrt(len(self.y_true))
def get_linear_fit(self):
"""
"""
if self.parameters == 'estimate':
slope_init = (self.y_true[-1] - self.y_true[0]) / (self.x[-1] - self.x[0])
b_init = np.mean([self.y_true[-1] - slope_init * self.x[-1], self.y_true[0] - slope_init * self.x[0]])
self.parameters = [slope_init, b_init]
elif not isinstance(self.parameters, (list, np.ndarray)):
raise ValueError("parameters = 'estimate' or [slope, y-intercept]")
meths = ['residuals', 'std of mean']
funcs = [get_error_by_residuals, get_error_by_std_mean]
func = dict(zip(meths, funcs))[self.method]
res = minimize(func, x0=self.parameters, args=(self,), method='Nelder-Mead')
self.parameters = [res.x[0], res.x[1]]
self.y_fit = get_y_fit(self)
self.residuals = get_residuals(self)
self.weights = update_weights(self)
return self.parameters, self.y_fit, self.residuals, self.weights
x = np.linspace(0, 4, 5)
y_true = np.linspace(5, 9, 5) ## using slope=1, y-intercept=5
y_actual = np.array([4.8, 6.2, 7, 8.1, 8.9]) ## test data
GLS = GeneralizedLeastSquares()
GLS.set_x(x)
GLS.set_y_true(y_actual)
GLS.set_weights(np.ones(len(x)))
GLS.set_parameters('estimate')
# GLS.set_parameters([1.2, 4.9])
GLS.set_method('residuals')
results = GLS.get_linear_fit()
print(results)
回答1:
Your method is not taking an argument. It should be:
def set_x(self, x):
self.x = x
Wrapping properties in get/set methods is a very Java / outdated way of doing things. It is much easier to access the underlying property outside of your class. I.e. rather than: GLS.set_x(12), consider the more Pythonic: GLS.x = 12. This way you don't have to write a get and set method for each property.
Also, it might make more sense for the heavy lifting method of your object, get_linear_fit to be put in the __call__ method. This way, you can run the regression using by just typing GLS() rather than GLS.get_linear_fit()
来源：https://stackoverflow.com/questions/46752045/how-can-i-pass-different-types-of-parameters-ex-array-into-a-functional-class