【发布时间】：2017-04-28 21:05:04
【问题描述】：
我想使用“双高斯”（即两个正态分布的归一化总和）对某些数据进行拟合。使用 SciPy 0.18.1，以下代码有效：
import numpy as np
from scipy.stats import rv_continuous
class DoubleGauss(rv_continuous):
"""Double Gaussian distribution"""
def _pdf(self, x, mu1, sigma1, mu2, sigma2, w):
g1 = np.exp(-0.5*((x-mu1)/sigma1)**2) / np.sqrt(2.0*np.pi*sigma1**2)
g2 = np.exp(-0.5*((x-mu2)/sigma2)**2) / np.sqrt(2.0*np.pi*sigma2**2)
return w * g1 + (1.0-w) * g2
dg = DoubleGauss(name='DG')
print dg.rvs(mu1=0.001, sigma1=2.0, mu2=0.05, sigma2=4.0, w=0.8)
（这当然是一个最小的例子。最后，我还将重新定义 _cdf 以表示速度，并重新定义 _argcheck 以允许 mu 参数的非零值。）
因为我需要使用其他一些库读取要拟合的数据，所以我必须在只有 SciPy 0.8.0 可用的环境中运行代码。但是，运行相同的代码会导致此错误：
File "test.py", line 13, in <module>
print dg.rvs(mu1=0.01, sigma1=2.0, mu2=0.05, sigma2=4.0, w=0.8)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 523, in rvs
vals = self._rvs(*args)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 848, in _rvs
Y = self._ppf(U,*args)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 861, in _ppf
return self.vecfunc(q,*args)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-numpy/1.6.1-cms/lib/python2.7/site-packages/numpy/lib/function_base.py", line 1862, in __call__
theout = self.thefunc(*newargs)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 817, in _ppf_single_call
return optimize.brentq(self._ppf_to_solve, self.xa, self.xb, args=(q,)+args, xtol=self.xtol)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/optimize/zeros.py", line 362, in brentq
r = _zeros._brentq(f,a,b,xtol,maxiter,args,full_output,disp)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 814, in _ppf_to_solve
return apply(self.cdf, (x, )+args)-q
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 952, in cdf
place(output,cond,self._cdf(*goodargs))
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 855, in _cdf
return self.veccdf(x,*args)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-numpy/1.6.1-cms/lib/python2.7/site-packages/numpy/lib/function_base.py", line 1862, in __call__
theout = self.thefunc(*newargs)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/stats/distributions.py", line 852, in _cdf_single_call
return scipy.integrate.quad(self._pdf, self.a, x, args=args)[0]
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/integrate/quadpack.py", line 247, in quad
retval = _quad(func,a,b,args,full_output,epsabs,epsrel,limit,points)
File "/cvmfs/cms.cern.ch/slc6_amd64_gcc491/external/py2-scipy/0.8.0-cms/lib/python2.7/site-packages/scipy/integrate/quadpack.py", line 313, in _quad
return _quadpack._qagie(func,bound,infbounds,args,full_output,epsabs,epsrel,limit)
TypeError: _pdf() takes exactly 7 arguments (2 given)
在文档中，我发现如何使用 rv_continuous 的描述没有差异。如何修复代码以使其适用于 SciPy 0.8.0？
【问题讨论】：
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Scipy 0.8。哇。第一个猜测：在 0.13.0 之前，pdf 等人不接受关键字参数。尝试将它们作为位置参数？
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我需要考虑一下您的意思，但它确实有效。我只需要执行
print dg.rvs(0.01, 2.0, 0.05, 4.0, 0.8)即可获得运行代码。谢谢！