python – 在类中创建类的副本

2019年8月4日 165次阅读

我想在
python中对代码进行cython化以加速代码.在下面你可以看到我尝试使我的python类可以理解为cython：

import numpy as np
cimport numpy as np
ctypedef np.double_t DTYPE_T
cpdef double std_G,v_c
std_G=4.3e-9 # Newton's const   in Mpc (km/s)^2 M_sol^{-1}
v_c = 299792.458 #km/s

cdef extern from "math.h":
    double log(double) nogil
    double sqrt(double) nogil


cdef extern from "gsl/gsl_math.h":
    ctypedef struct gsl_function:
        double (* function) (double x, void * params)
        void * params

cdef extern from "gsl/gsl_integration.h":
    ctypedef struct gsl_integration_workspace
    gsl_integration_workspace *  gsl_integration_workspace_alloc(size_t n)
    void  gsl_integration_workspace_free(gsl_integration_workspace * w)
    int  gsl_integration_qags(const gsl_function * f, double a, double b, double epsabs, double epsrel, size_t limit, gsl_integration_workspace * workspace, double *result, double *abserr)

cdef double do_callback(double x, void* params): 
     return (<ComovingDistMemoization>params).eval(x) 


cdef class ComovingDistMemoization(object):
     cdef list _memotable
     cdef cosmolgy
     def __cinit__(self, cosmology, memotable = None):

         if memotable is None:
            self._memotable = []

         self._memotable = memotable
         self.cosmology = cosmology
     def __call__(self, double z):


        if z in self._memotable:
            return self._memotable[z]

        def eval(z):

            return 1./sqrt(self.cosmology.hubble2(z))
        cdef gsl_integration_workspace* w =gsl_integration_workspace_alloc(1000)
        cdef gsl_function F            

        F.function = &do_callback 
        F.params = <void*>self 
        cdef double result = 3, error = 5
        cdef double y, err, dist
        gsl_integration_qags (&F, 0, z, 0, 1e-7, 1000, w, &result, &error) 
        y, err = result, error 

        gsl_integration_workspace_free(w) 

        dist = self.cosmology.v_c * y  #to get proper units, ie to put in the hubble length

        self._memotable[z] = dist

        return dist


cdef class cosmology(object):
    cdef comovingdist
    cdef public double omega_m, omega_l, h, w, omega_r, G, v_c
    cdef double H0, hubble_length
    def __init__(self, omega_m = 0.3, omega_l = 0.7, h = 0.7, w = -1, omega_r = 0., G = std_G):

        self.omega_m = omega_m
        self.omega_l = omega_l
        self.omega_r = omega_r
        self.h = h
        self.w = w
        self.G = G
        self.v_c = v_c

        self.comovingdist = ComovingDistMemoization(self)
    def __copy__(self):

        return cosmology(omega_m = self.omega_m, omega_l = self.omega_l, h = self.h, w = self.w, omega_r = self.omega_r, G = self.G)

    property H0:
       def __get__(self):
           return 100*self.h  #km/s/MPC

    def hubble2(self, double z):
        cdef double inv_a
        inv_a = 1.+z
        return (self.omega_r*inv_a**4 + self.omega_m*inv_a**3 + \
                  self.omega_l*(inv_a**(3*(1+self.w))) + (1 - self.omega_m - self.omega_l - self.omega_r)*inv_a**2)*self.H0**2

    property hubble_length:
        def __get__(self):
            return self.v_c / self.H0

    def rho_crit(self, double z):
        return 3.*self.hubble2(z)/(8*np.pi*self.G)


    def angulardist(self, double z, double z2 = None):

        if z2 is None:
            return self.comovingdist(z) / (1+z)

        return (self.comovingdist(z2) - self.comovingdist(z)) / (1+z2)

然而,其中一个引发错误的地方,到目前为止我找不到任何替换,我的调查刚刚达到这一点,cython不支持__copy __(self)函数.
第一个问题：如何在cython中复制一个类的方法？
我用pickle.Pickler读到了,有可能为类的实例提供替换,但我不知道它应该如何在类中生成类的副本？
更新：
用以下代码替换__copy__是一种正确的方法：

def __reduce__(self):
    return (self.__class__, (), self.__getstate__())
def __getstate__(self):
    return (self.omega_m, self.omega_l, self.omega_r, self.h, self.w, self.G, self.v_c)
def __setstate__(self, data):
    (self.omega_m, self.omega_l, self.omega_r, self.h, self.w, self.G, self.v_c) = data

我的第二个问题是关于属性,我是否在cython中定义了属性,或者我还需要一个__set__函数？

我的最后一个问题：当我使用ComovingDistMemoization调用所有宇宙学类的实例时,它们返回零.我想知道我在ComovingDistMemoization类中调用cosmology类的方式,反之亦然导致问题,并且不能在它们之间传递信息？

最佳答案 回答你的第二个问题,在你的情况下,你不需要__set__函数,似乎你使用__get__概念的方式有误.要获取的属性名称必须设置为：

def get_H0(self):
   return 100*self.h  #km/s/MPC
H0 = property(fget=get_H0)

def get_hubble_length(self):
    return self.v_c / self.H0
hubble_length = property(fget=get_hubble_length)

编辑：我不知道@property不能与Cython一起使用

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