swig c++ to python (with numpy): error: use of undeclared identifier 'import_array'

OS: macOS Sierra 10.12.4

python distribution: Anaconda python 3.6

I'm learning how to pass numpy array to c++ with distutils.

There is an error occured when I run:

$ python setup.py build_ext

error:

sample_wrap.cpp:4571:3: error: use of undeclared identifier 'import_array'
  import_array();
  ^
1 error generated.

file: sample.i

/* file: sample.i */
%module sample
%{
/* include C++ header files necessary to compile the interface */
#include "src/sample.h"
%}

%include "typemaps.i"
%include "src/numpy.i"
%init %{
import_array();
%}

%apply (int DIM1, double* IN_ARRAY1) {(int n, double *a), (int m, double *b)};
%apply (int DIM1, double* ARGOUT_ARRAY1) {(int size, double *arr)};

%include "src/sample.h"

file: setup.py

# ----- file: setup.py -----

from distutils.core import setup, Extension
import numpy
import os

name = "sample"    # name of the module
version = "1.0"        # the module's version number

os.environ['CC'] = 'g++';
os.environ['CXX'] = 'g++';

setup(name=name, version=version,
    ext_modules=[Extension(name='_sample',
                           sources=["sample.i", "src/sample.cpp"],
                           include_dirs=['src',numpy.get_include()],
                           swig_opts=["-c++"]
                           )]
    )

file: src/sample.cpp

/* ----- file: src/sample.cpp ----- */

#include <cmath>
#include "sample.h"

double dot(int n, double *a, int m, double *b){
    double sum = 0.0;
    for (int i=0; i<n; ++i){
      sum += a[i]*b[i];
    }
    return sum;
}

void arange(int size, double *arr){
    for (int i=0; i<size; ++i)
    arr[i] = i;
}

file: src/sample.h

/* ----- file: src/sample.h ----- */

#ifndef SAMPLE_H_
#define SAMPLE_H_

double dot(int n, double *a, int m, double *b);
void arange(int size, double *arr);

#endif // SAMPLE_H_

I've tried to change os.environ['CC'] = 'g++' and os.environ['CXX'] = 'g++' to os.environ['CC'] = 'g++-6' and os.environ['CXX'] = 'g++-6' in setup.py, in order to compiling with GUN g++ not clang, but still get similar error:

sample_wrap.cpp: In function 'PyObject* PyInit__sample()':
sample_wrap.cpp:4571:16: error: 'import_array' was not declared in this scope
   import_array();
                ^

I would try adding #define SWIG_FILE_WITH_INIT based on this documentation

/* file: sample.i */
%module sample
%{
#define SWIG_FILE_WITH_INIT
#include "src/sample.h"
%}