如何访问从scipy.optimize.basinhopping返回的OptimizeResult实例的`success`属性（不最小化？）>

Question

问题

根据SciPy docs，函数scipy.optimize.basinhopping(...)返回OptimizeResult的实例，该实例基本上是字典的包装器。我可以print该实例并查看success: True，但是我想以编程方式访问它。在通过scipy.optimize.minimize(...)进行局部最小化的情况下-根据SciPy docs，它还会返回OptimizeResult的实例-success值可以作为OptimizeResult.success进行访问。但是，这不适用于basinhopping例程。我觉得这很奇怪，因为SciPy docs的OptimizeResult显示success应该是允许的键。

我的问题

如何以编程方式访问success的OptimizeResult值？

示例代码

要重新创建此问题（并显示它在minimize(...)的情况下有效），请参见下面的代码：

import numpy as np
from scipy.optimize import minimize, basinhopping, OptimizeResult

def pdf(prms, x):
    """ normal distribution pdf """
    return np.exp(- np.square((x - prms[0])/prms[1]) / 2) / (prms[1] * np.sqrt(2 * np.pi))

def nll(prms, x):
    """ negative log-likelihood """
    return np.log(pdf(prms, x))

def err_func(prms, x):
    """ maximum likelihood estimation """
    return -1 * np.sum(nll(prms, x))

prms = (50, 10) # true parameters: mean=50, std=10
data = np.random.normal(loc=prms[0], scale=prms[1], size=1000) # normal distribution
x0 = (30, 15) # initial parameter guess

local_result = minimize(err_func, x0, args=(data,), method='Nelder-Mead')
print("\n LOCAL EXTREMUM RESULT:\n{}\n".format(local_result))
print("\n .. LOCAL SUCCESS:\n{}\n".format(local_result.success))

minimizer_kwargs = {'args' : (data,), 'method' : 'Nelder-Mead'}
global_result = basinhopping(err_func, x0, minimizer_kwargs=minimizer_kwargs)
print("\n GLOBAL EXTREMUM RESULT:\n{}\n".format(global_result))
try:
    print("\n .. GLOBAL SUCCESS:\n{}\n".format(global_result.success))
except:
    suc = OptimizeResult(global_result)
    print("\n .. GLOBAL SUCCESS:\n{}\n".format(suc.success)) 
示例输出

上面的print语句输出以下内容：

 LOCAL EXTREMUM RESULT:
 final_simplex: (array([[49.81697641, 10.07216849],
       [49.81705723, 10.07218614],
       [49.81706317, 10.07208372]]), array([3728.71186314, 3728.71186315, 3728.71186316]))
           fun: 3728.711863138763
       message: 'Optimization terminated successfully.'
          nfev: 86
           nit: 44
        status: 0
       success: True
             x: array([49.81697641, 10.07216849])


 .. LOCAL SUCCESS:
True


 GLOBAL EXTREMUM RESULT:
                        fun: 3728.711863121894
 lowest_optimization_result:  final_simplex: (array([[49.81701209, 10.07213731],
       [49.81709255, 10.07216525],
       [49.81703196, 10.07220361]]), array([3728.71186312, 3728.71186315, 3728.71186316]))
           fun: 3728.711863121894
       message: 'Optimization terminated successfully.'
          nfev: 63
           nit: 31
        status: 0
       success: True
             x: array([49.81701209, 10.07213731])
                    message: ['requested number of basinhopping iterations completed successfully']
      minimization_failures: 0
                       nfev: 6455
                        nit: 100
                          x: array([49.81701209, 10.07213731])

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/scipy/optimize/optimize.py", line 114, in __getattr__
    return self[name]
KeyError: 'success'



During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "stacko.py", line 28, in <module>
    print("\n .. GLOBAL SUCCESS:\n{}\n".format(global_result.success))
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/scipy/optimize/optimize.py", line 116, in __getattr__
    raise AttributeError(name)
AttributeError: success

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/scipy/optimize/optimize.py", line 114, in __getattr__
    return self[name]
KeyError: 'success'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "stacko.py", line 31, in <module>
    print("\n .. GLOBAL SUCCESS:\n{}\n".format(suc.success))
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/scipy/optimize/optimize.py", line 116, in __getattr__
    raise AttributeError(name)
AttributeError: success

问题根据SciPy文档，函数scipy.optimize.basinhopping（...）返回OptimizeResult的实例，该实例基本上是字典的包装。我可以打印此...

Answer 1

[global_result结果具有属性lowest_optimization_result，它本身是OptimizeResult的实例，因此您应该调用该属性的success：