让 distutils 在正确的位置查找 numpy 头文件

Question

在我的安装中，numpy 的arrayobject.h 位于…/site-packages/numpy/core/include/numpy/arrayobject.h。我写了一个使用 numpy 的简单 Cython 脚本：

cimport numpy as np

def say_hello_to(name):
    print("Hello %s!" % name)

我还有以下 distutils setup.py（复制自Cython user guide）：

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

ext_modules = [Extension("hello", ["hello.pyx"])]

setup(
  name = 'Hello world app',
  cmdclass = {'build_ext': build_ext},
  ext_modules = ext_modules
)

当我尝试使用 python setup.py build_ext --inplace 构建时，Cython 会尝试执行以下操作：

gcc -fno-strict-aliasing -Wno-long-double -no-cpp-precomp -mno-fused-madd \
-fno-common -dynamic -DNDEBUG -g -Os -Wall -Wstrict-prototypes -DMACOSX \
-I/usr/include/ffi -DENABLE_DTRACE -arch i386 -arch ppc -pipe \
-I/System/Library/Frameworks/Python.framework/Versions/2.5/include/python2.5 \
-c hello.c -o build/temp.macosx-10.5-i386-2.5/hello.o

可以预见的是，这找不到arrayobject.h。如何让 distutils 使用 numpy 包含文件的正确位置（不让用户定义 $CFLAGS）？

Answer 1

使用numpy.get_include():

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
import numpy as np                           # <---- New line

ext_modules = [Extension("hello", ["hello.pyx"],
                                  include_dirs=[get_numpy_include()])]   # <---- New argument

setup(
  name = 'Hello world app',
  cmdclass = {'build_ext': build_ext},       
  ext_modules = ext_modules
)

Answer 2

对于不使用 Cython 的任何人，如果您只是从 distutils.command.build_ext 而不是 Cython 导入 build_ext，则可以对 R_Beagrie 的解决方案进行轻微修改而不依赖于该依赖项。

from distutils.core import setup
from distutils.extension import Extension
from distutils.command.build_ext import build_ext

class CustomBuildExtCommand(build_ext):
    """build_ext command for use when numpy headers are needed."""
    def run(self):

        # Import numpy here, only when headers are needed
        import numpy

        # Add numpy headers to include_dirs
        self.include_dirs.append(numpy.get_include())

        # Call original build_ext command
        build_ext.run(self)

ext_modules = [Extension("hello", ["hello.c"])]

setup(
  name = 'Hello world app',
  cmdclass = {'build_ext': CustomBuildExtCommand},
  install_requires=['numpy'],
  ext_modules = ext_modules
)

Answer 3

@vebjorn-ljosa 给出的答案是正确的，但与install_requires=['numpy'] 结合使用时会出现问题。在这种情况下，你的 setup.py 需要导入 numpy，如果你在没有先运行 pip install numpy 的情况下尝试 pip install 你的项目会导致错误。

如果您的项目依赖于 numpy，并且您希望 numpy 作为依赖项自动安装，则仅在实际构建扩展时才需要设置 include_dirs。你可以通过继承build_ext来做到这一点：

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

class CustomBuildExtCommand(build_ext):
    """build_ext command for use when numpy headers are needed."""
    def run(self):

        # Import numpy here, only when headers are needed
        import numpy

        # Add numpy headers to include_dirs
        self.include_dirs.append(numpy.get_include())

        # Call original build_ext command
        build_ext.run(self)

ext_modules = [Extension("hello", ["hello.pyx"])]

setup(
  name = 'Hello world app',
  cmdclass = {'build_ext': CustomBuildExtCommand},
  install_requires=['numpy'],
  ext_modules = ext_modules
)

您可以使用类似的技巧将 cython 添加为自动安装的依赖项：

from distutils.core import setup
from distutils.extension import Extension

try:
    from Cython.setuptools import build_ext
except:
    # If we couldn't import Cython, use the normal setuptools
    # and look for a pre-compiled .c file instead of a .pyx file
    from setuptools.command.build_ext import build_ext
    ext_modules = [Extension("hello", ["hello.c"])]
else:
    # If we successfully imported Cython, look for a .pyx file
    ext_modules = [Extension("hello", ["hello.pyx"])]

class CustomBuildExtCommand(build_ext):
    """build_ext command for use when numpy headers are needed."""
    def run(self):

        # Import numpy here, only when headers are needed
        import numpy

        # Add numpy headers to include_dirs
        self.include_dirs.append(numpy.get_include())

        # Call original build_ext command
        build_ext.run(self)

setup(
  name = 'Hello world app',
  cmdclass = {'build_ext': CustomBuildExtCommand},
  install_requires=['cython', 'numpy'],
  ext_modules = ext_modules
)

注意：这些方法仅适用于 pip install .。它们不适用于python setup.py install 或python setup.py develop，因为这些命令会导致依赖项安装在您的项目之后，而不是之前。