修改函数内的全局变量

Question

我已经定义了以下功能:

def GMM(s1, s2, s3, s4, s5, a):
    """The GMM objective function.

    Arguments
    ---------
        si: float
            standard deviations of preference distribution

        a: float
            marginal utility of residutal income

    Paramters
    ---------
        Px: array (1,ns) 
            projector onto nonprice characteristic space

        xk, z: arrays (J, 5) and (J, 12)
            nonprice char. and instruments

        invW: array (12, 12) 
            GMM weight matrix

    Returns
    -------
        float."""
    delta = invert(s1, s2, s3, s4, s5, a, delta0) # Invert market shares to get mean utility
    bmean = np.dot(Px, delta)                     # Project delta onto charancteristic space
    xihat = delta - np.dot(xk, bmean)             # Compute implied unobservable prod. quality
    temp1 = np.dot(xihat.T, z)
    if np.any(np.isnan(delta)) == True:
        value = 1e+10
    else:
        value = np.dot(np.dot(temp1, invW), temp1.T)
    return np.sqrt(value)

我的问题涉及delta函数内部的变量绑定.在函数之外我将设置初始值delta0.现在,最终我将最小化此功能.我希望发生的是每次函数GMM评估时,delta从之前的评估中用作新的delta0.我尝试将其定义delta0为全局变量,但它似乎没有用......可能这是我的错误.虽然,我在这里读到,一般来说这是一个糟糕的方法.有什么建议？

Answer 1

有多种方法可以实现您的目标.在以下示例中,delta保存在函数调用之间.

1-级

class Example:
  def __init__(self, value):
    self.delta = value
  def gmm(self):
    self.delta += 1
    return self.delta

e = Example(0)
print e.gmm()

2-发电机

def gmm():
  delta = 0
  while True:
    delta += 1
    yield delta

for v in gmm():
  print v

3-功能属性

def gmm():
  gmm.delta += 1
  return delta
gmm.delta = 0

4-全局变量(如你所说的那样气馁):

delta = 0
def gmm():
  global delta
  delta += 1
  return delta

等等...

Answer 2

globalVariable = 0

def test():
    global globalVariable
    globalVariable = 10

test()
print globalVariable

您可以通过这种方式编辑全局变量.