Dear Numerical Python Users, I have a small program that produces array's that I want to import in Python. The code is organised in three files. 1) arraytest.h, 2) arraytest.c 3) testmodule.c. and the code is shown below. The function myTest() produces the array and is called from the test module. However, the program does not work! it crashes. In my opinion, I do not have yet enough insight in Numerical Python. Is there an essential part that I do not understand. Remarkable is that the pure Python equivalent of the program does not crash. Any ideas? Wim Vanroose ///////////////////////// //file: arraytest.h ////////////////////// #include "Python.h" #include "arrayobject.h" PyObject *myTest(void); ////////////////////// // file: arraytest.c //////////////////// #include "arraytest.h" PyObject * myTest(void ){ PyArrayObject *result; double *datainput; int dimensions[1]; int M=10; int MM; dimensions[0]=M; result = (PyArrayObject *)PyArray_FromDims(1,dimensions,PyArray_DOUBLE); datainput =(double *)result->data; for(MM=0;MM < M ; MM++){ datainput[MM] = MM*0.1; } return PyArray_Return(result); } //////////////////// //file: test.c CRASHES!!!! //////////////// #include "arraytest.h" static PyObject *function(PyObject *self, PyObject *args){ return myTest(); } static PyMethodDef testMethods[] = { {"test",function,1}, {NULL,NULL} }; extern "C" { void inittest(){ PyObject *m,*d; m = Py_InitModule("test", testMethods); import_array(); d = PyModule_GetDict(m); } %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The Python Equivalent: DOES NOT CRASH %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ///////////// // file: simpletest.h ///////////////// #include "simpletest.h" PyObject * myTest(void); //////////////////// // file: test.c ////////////////////// #include "simpletest.h" PyObject * myTest(void ){ return Py_BuildValue("i",123); } //////////////// //file: test.c ////////////////// #include "simpletest.h" static PyObject *function(PyObject *self, PyObject *args){ return myTest(); } static PyMethodDef testMethods[] = { {"test",function,1}, {NULL,NULL} }; extern "C" { void inittest(){ PyObject *m,*d; m = Py_InitModule("test", testMethods); d = PyModule_GetDict(m); }
I don't know if someone helped you with this while I was on travel, but in case they didn't: I'm pretty sure your problem is that myTest is not in the same file as the import_array; when it tries to access the Numeric C API, it will be dereferencing zero. For extensions that are not in one file, a special techniques is required. Recently an improvement was added to make this easier. I believe you should add this to your header file, above the include of arrayobject.h: #define PY_ARRAY_UNIQUE_SYMBOL xxxx where xxxx is any name you choose that won't conflict with your other stuff. I hope that if I have this wrong somebody will correct me. -----Original Message----- From: numpy-discussion-admin@lists.sourceforge.net [mailto:numpy-discussion-admin@lists.sourceforge.net]On Behalf Of Wim Vanroose Sent: Tuesday, July 24, 2001 4:05 AM To: numpy-discussion@lists.sourceforge.net Subject: [Numpy-discussion] Troubles with arrays Dear Numerical Python Users, I have a small program that produces array's that I want to import in Python. The code is organised in three files. 1) arraytest.h, 2) arraytest.c 3) testmodule.c. and the code is shown below. The function myTest() produces the array and is called from the test module. However, the program does not work! it crashes. In my opinion, I do not have yet enough insight in Numerical Python. Is there an essential part that I do not understand. Remarkable is that the pure Python equivalent of the program does not crash. Any ideas? Wim Vanroose ///////////////////////// //file: arraytest.h ////////////////////// #include "Python.h" #include "arrayobject.h" PyObject *myTest(void); ////////////////////// // file: arraytest.c //////////////////// #include "arraytest.h" PyObject * myTest(void ){ PyArrayObject *result; double *datainput; int dimensions[1]; int M=10; int MM; dimensions[0]=M; result = (PyArrayObject *)PyArray_FromDims(1,dimensions,PyArray_DOUBLE); datainput =(double *)result->data; for(MM=0;MM < M ; MM++){ datainput[MM] = MM*0.1; } return PyArray_Return(result); } //////////////////// //file: test.c CRASHES!!!! //////////////// #include "arraytest.h" static PyObject *function(PyObject *self, PyObject *args){ return myTest(); } static PyMethodDef testMethods[] = { {"test",function,1}, {NULL,NULL} }; extern "C" { void inittest(){ PyObject *m,*d; m = Py_InitModule("test", testMethods); import_array(); d = PyModule_GetDict(m); } %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The Python Equivalent: DOES NOT CRASH %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ///////////// // file: simpletest.h ///////////////// #include "simpletest.h" PyObject * myTest(void); //////////////////// // file: test.c ////////////////////// #include "simpletest.h" PyObject * myTest(void ){ return Py_BuildValue("i",123); } //////////////// //file: test.c ////////////////// #include "simpletest.h" static PyObject *function(PyObject *self, PyObject *args){ return myTest(); } static PyMethodDef testMethods[] = { {"test",function,1}, {NULL,NULL} }; extern "C" { void inittest(){ PyObject *m,*d; m = Py_InitModule("test", testMethods); d = PyModule_GetDict(m); } _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net http://lists.sourceforge.net/lists/listinfo/numpy-discussion
On Fri, 27 Jul 2001, Paul F. Dubois wrote:
I don't know if someone helped you with this while I was on travel, but in case they didn't:
I tested his code on my machine and found that by placing an import_array() statement in the subroutine which uses the C-API seems to work.
I'm pretty sure your problem is that myTest is not in the same file as the import_array; when it tries to access the Numeric C API, it will be dereferencing zero. For extensions that are not in one file, a special techniques is required. Recently an improvement was added to make this easier. I believe you should add this to your header file, above the include of arrayobject.h:
#define PY_ARRAY_UNIQUE_SYMBOL xxxx
where xxxx is any name you choose that won't conflict with your other stuff.
participants (3)
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Paul F. Dubois -
Travis Oliphant -
Wim Vanroose