我正在将Cython内存视图转换为numpy数组（能够在纯Python代码中使用它）：
from libc.stdlib cimport realloc
cimport numpy as np
DTYPE = np.float64
ctypedef np.float64_t DTYPE_t
cpdef np.ndarray[DTYPE_t] compute(DTYPE_t[:,::1] data):
cdef unsigned int Nchannels = data.shape[0]
cdef unsigned int Ndata = data.shape[1]
cdef DTYPE_t* output = NULL
cdef DTYPE_t[::1] mv
output = <DTYPE_t*>realloc(output, Ndata*sizeof(output))
if not output:
raise MemoryError()
mv = <DTYPE_t[:Ndata]>output
mv[10:Ndata-10] = 0.0
# various calculations...
return np.asarray(mv, dtype=DTYPE, order='C')
它编译，但编译器发出以下警告：
/Users/vlad/anaconda/lib/python2.7/site-packages/numpy/core/include
/nump/npy_1_7_deprecated_api.h:15:2: warning:
"Using deprecated NumPy API, disable it by #defining NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION" [-W#warnings]
我在setup.py中添加了建议的指令：
from distutils.core import setup, Extension
from Cython.Build import cythonize
import numpy
filename = 'agents3.pyx'
agents_module = Extension(
'Agents',
sources = [filename],
define_macros = [('NPY_NO_DEPRECATED_API', 'NPY_1_7_API_VERSION')],
include_dirs = [numpy.get_include()],
)
setup (name = 'Agents',
ext_modules = cythonize(agents_module)
)
现在它不会编译，它说：
Vlads-MacBook-Pro:program vlad$ python setup.py build_ext --inplace
Compiling agents3.pyx because it changed.
Cythonizing agents3.pyx
running build_ext
building 'Agents' extension
gcc -fno-strict-aliasing -I/Users/vlad/anaconda/include -arch x86_64 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DNPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION -I/Users/vlad/anaconda/lib/python2.7/site-packages/numpy/core/include -I/Users/vlad/anaconda/include/python2.7 -c agents3.c -o build/temp.macosx-10.5-x86_64-2.7/agents3.o
agents3.c:2273:52: error: use of undeclared identifier 'NPY_C_CONTIGUOUS'
__pyx_t_2 = ((!(PyArray_CHKFLAGS(__pyx_v_self, NPY_C_CONTIGUOUS) != 0)) != 0);
^
agents3.c:2311:52: error: use of undeclared identifier 'NPY_F_CONTIGUOUS'
__pyx_t_1 = ((!(PyArray_CHKFLAGS(__pyx_v_self, NPY_F_CONTIGUOUS) != 0)) != 0);
^
agents3.c:2474:42: error: no member named 'descr' in 'struct tagPyArrayObject'
__pyx_t_4 = ((PyObject *)__pyx_v_self->descr);
~~~~~~~~~~~~ ^
agents3.c:4026:27: error: no member named 'base' in 'struct tagPyArrayObject'
Py_XDECREF(__pyx_v_arr->base);
~~~~~~~~~~~ ^
/Users/vlad/anaconda/include/python2.7/object.h:823:34: note: expanded from macro 'Py_XDECREF'
#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
^
agents3.c:4026:27: error: no member named 'base' in 'struct tagPyArrayObject'
Py_XDECREF(__pyx_v_arr->base);
~~~~~~~~~~~ ^
/Users/vlad/anaconda/include/python2.7/object.h:823:64: note: expanded from macro 'Py_XDECREF'
#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
^
/Users/vlad/anaconda/include/python2.7/object.h:772:24: note: expanded from macro 'Py_DECREF'
--((PyObject*)(op))->ob_refcnt != 0) \
^
agents3.c:4026:27: error: no member named 'base' in 'struct tagPyArrayObject'
Py_XDECREF(__pyx_v_arr->base);
~~~~~~~~~~~ ^
/Users/vlad/anaconda/include/python2.7/object.h:823:64: note: expanded from macro 'Py_XDECREF'
#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
^
/Users/vlad/anaconda/include/python2.7/object.h:775:34: note: expanded from macro 'Py_DECREF'
_Py_Dealloc((PyObject *)(op)); \
^
/Users/vlad/anaconda/include/python2.7/object.h:762:15: note: expanded from macro '_Py_Dealloc'
(*Py_TYPE(op)->tp_dealloc)((PyObject *)(op)))
^
/Users/vlad/anaconda/include/python2.7/object.h:115:47: note: expanded from macro 'Py_TYPE'
#define Py_TYPE(ob) (((PyObject*)(ob))->ob_type)
^
agents3.c:4026:27: error: no member named 'base' in 'struct tagPyArrayObject'
Py_XDECREF(__pyx_v_arr->base);
~~~~~~~~~~~ ^
/Users/vlad/anaconda/include/python2.7/object.h:823:64: note: expanded from macro 'Py_XDECREF'
#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
^
/Users/vlad/anaconda/include/python2.7/object.h:775:34: note: expanded from macro 'Py_DECREF'
_Py_Dealloc((PyObject *)(op)); \
^
/Users/vlad/anaconda/include/python2.7/object.h:762:45: note: expanded from macro '_Py_Dealloc'
(*Py_TYPE(op)->tp_dealloc)((PyObject *)(op)))
^
agents3.c:4035:16: error: no member named 'base' in 'struct tagPyArrayObject'
__pyx_v_arr->base = __pyx_v_baseptr;
~~~~~~~~~~~ ^
agents3.c:4070:30: error: no member named 'base' in 'struct tagPyArrayObject'
__pyx_t_1 = ((__pyx_v_arr->base == NULL) != 0);
~~~~~~~~~~~ ^
agents3.c:4093:44: error: no member named 'base' in 'struct tagPyArrayObject'
__Pyx_INCREF(((PyObject *)__pyx_v_arr->base));
~~~~~~~~~~~ ^
agents3.c:1065:37: note: expanded from macro '__Pyx_INCREF'
#define __Pyx_INCREF(r) Py_INCREF(r)
^
/Users/vlad/anaconda/include/python2.7/object.h:767:18: note: expanded from macro 'Py_INCREF'
((PyObject*)(op))->ob_refcnt++)
^
agents3.c:4094:41: error: no member named 'base' in 'struct tagPyArrayObject'
__pyx_r = ((PyObject *)__pyx_v_arr->base);
~~~~~~~~~~~ ^
11 errors generated.
error: command 'gcc' failed with exit status 1
Vlads-MacBook-Pro:program vlad$
我该怎么办？可以保留已弃用的API调用吗？它试图访问base字段 - 但我没有这样做，这是Cython的错。我只是将一个内存视图转换为一个numpy数组。是否有另一种更清洁/更安全的方法呢？
答案 0 :(得分：38)
仅供进一步参考，cython online docs说这是因为Cython使用的是已弃用的Numpy API，目前只是警告，我们可以忽略它。
答案 1 :(得分：0)
我也得到同样的警告，我说这是正常的。
使用numpy C API，如果你不喜欢这个警告，你需要在C脚本前放一行，但它只是告诉编译器忽略“不赞成”的消息 - 它似乎工作了两种方式相同。
我猜测Cython编译器在生成C代码时没有放入这行代码，我认为这不重要。
答案 2 :(得分：0)
假设有人希望隐藏弃用警告，可以使用clang extra_compile_args=['-Wno-#warnings']实现以下编译器标志。
对于gcc，extra_compile_args=['-Wno-cpp']实现了相同的目标。
当然，这也隐藏了其他预处理器指令警告。