使用numba进行特殊功能

问题描述

此代码失败：

import numpy as np
from numba import jit
import scipy.special as sp

@jit(nopython=True)
def f(a):
    return sp.xlogy(a,a)
  

a = np.array([1,2,1],dtype=float)
f(a)

出现以下错误

TypingError: Failed in nopython mode pipeline (step: nopython frontend)
Unknown attribute 'xlogy' of type Module(<module 'scipy.special' from '/home/yair/.local/lib/python3.8/site-packages/scipy/special/__init__.py'>)

但是，我认为它应该起作用，因为它说here可能会使xlogy超载。 answer from 2015表示无法完成此操作（对于某些其他功能），但也许我认为它已更改。

当然，我可以自己实现它，但是使用已知的解决方案会很好。

编辑： 根据以下Andras Deak的建议，我尝试使用numba-scipy。我无法使其正常工作，并希望提供一些用法示例。这是我的尝试-均失败，请参见以下错误：

import numpy as np
from numba import jit
import numba_scipy
import scipy as sp
from scipy import special as spc

@jit(nopython=True)
def f1(a):
    return numba_scipy.special.xlogy(a,a)

@jit(nopython=True)
def f2(a):
    return numba_scipy.xlogy(a,a)


@jit(nopython=True)
def f3(a):
    return sp.special.xlogy(a,a)

@jit(nopython=True)
def f4(a):
    return spc.xlogy(a,a)


a = np.array([0,1,2])

try:
    f1(a)
except Exception as e:
    print('f1 fails')
    print(e)

try:
    f2(a)
except Exception as e:
    print('f2 fails')
    print(e)

try:
    f3(a)
except Exception as e:
    print('f3 fails')
    print(e)

try:
    f4(a)
except Exception as e:
    print('f4 fails')
    print(e)

完整的错误消息：

/home/yair/.local/lib/python3.8/site-packages/numba/core/dispatcher.py:238: UserWarning: Numba extension module 'numba_scipy' failed to load due to 'ValueError(No function '__pyx_fuse_0pdtr' found in __pyx_capi__ of 'scipy.special.cython_special')'.
  entrypoints.init_all()
f1 fails
Failed in nopython mode pipeline (step: nopython rewrites)
module 'numba_scipy' has no attribute 'special'
f2 fails
Failed in nopython mode pipeline (step: nopython rewrites)
module 'numba_scipy' has no attribute 'xlogy'
f3 fails
Failed in nopython mode pipeline (step: nopython frontend)
Unknown attribute 'xlogy' of type Module(<module 'scipy.special' from '/home/yair/.local/lib/python3.8/site-packages/scipy/special/__init__.py'>)

File "example.py",line 19:
    def f3(a):
        return sp.special.xlogy(a,a)
        ^

During: typing of get attribute at example.py (19)

File "example.py",a)
        ^

f4 fails
Failed in nopython mode pipeline (step: nopython frontend)
Unknown attribute 'xlogy' of type Module(<module 'scipy.special' from '/home/yair/.local/lib/python3.8/site-packages/scipy/special/__init__.py'>)

File "example.py",line 23:
    def f4(a):
        return spc.xlogy(a,a)
        ^

During: typing of get attribute at example.py (23)

File "example.py",a)
        ^

解决方法

由于您在评论中遇到安装问题，因此我特别建议您使用numba本身（numba-scipy）的创建者使用的link to pypi。对包使用第一方扩展始终是一个好主意。

---

very documentation you linked与numba_special相关。如果您查看main page，将会看到第一个示例：

>>> import numba
>>> import scipy.special as sc
>>> import numba_special  # The import generates Numba overloads for special
>>> @numba.njit
... def gamma_plus_1(x):
...     return sc.gamma(x) + 1.0
...
>>> gamma_plus_1(5.0)
25.0

请注意您缺少的import numba_special行。

您还必须先安装numba-special。还要注意项目页面上的警告：

安装

Numba的特殊性取决于SciPy和Numba。在Numba版本中包含this issue的修复程序之前，必须在Numba的主分支上安装numba_special。

,

您正在从scipy.special调用xlogy函数，实际上，对于@jit装饰的函数调用的函数也需要进行@jit装饰。 这就是为什么xlogy与您的f函数和numba投掷错误不兼容的原因。解决方法可能是：

import numpy as np
from numba import jit


@jit(nopython=True)
def myxlogy(x,y):
    return x*np.log(y)


@jit(nopython=True)
def f(a):
    return myxlogy(a,a)

a = np.array([1,2,1],dtype=float)
f(a)
>>array([0.,1.38629436,nan,0.        ])