/* simple example of how to pass a multidimensional numarray array from
   python to C, and be able to address it as A[i][j].

   from numarray import *
   a = arange(36)
   a.shape = (6,6)

   import arraylib
   arraylib.print(a)

*/

#include "Python.h"
#include "numarray/numarray.h"
#include "numarray/libnumarray.h"
 
 
static PyObject *dump(PyObject *self, PyObject *args) {
 
  PyObject *oArray;
  PyArrayObject *pArray;
 
  double **cArray;
  int nx, ny;
  double *pData;

  int i, j;

  /* parse the argument list -- only take one argument, a numarray array */
  if (!PyArg_ParseTuple(args, "O",
                        &oArray))
    return NULL;
 
  pArray = NA_InputArray(oArray, tFloat64, NUM_C_ARRAY);
 
  if (!pArray) {
    printf("ERROR in arraylib.print: invalid parameters\n");
    return NULL;
  }
 
  /* at the moment, we expect the array to be two-dimensional.  It is 
     straightforward to extend this to higher dimensions */
  if (pArray->nd != 2) {
    printf("ERROR in arraylib.print: array must have 2 dimensions\n");
    return NULL;
  }
 
  nx = pArray->dimensions[0];
  ny = pArray->dimensions[1];
 
     
  /* we could access the array now, through one-dimensional indexing 
   *
   *   pData = (double *) pArray->data;
   *   for (i = 0; i < nx*ny; i++) {
   *     printf ("%f\n", pData[i]);
   *   }
   */
 
  /* but instead, we want to be able to index it as a multidimensional C array.
     so we use a double ** pointer to make indexing easier */
  cArray = (double **) malloc(sizeof(double *)*nx);
 
  for (i = 0; i < nx; i++) {
    cArray[i] = (double *) NA_OFFSETDATA(pArray) + i*ny;
  }
 
  /* now cArray[i][j] points to the relevant portions of the pArray data
     field */
  for (i = 0; i < nx; i++) {
    for (j = 0; j < ny; j++) {
      printf("%f ", cArray[i][j]);
    }
    printf("\n");
  }
 
  free(cArray);
 
  Py_XDECREF(pArray); 

  return Py_BuildValue("i", 1);
 
}
  
 
static PyMethodDef arraylibmethods[] = {
  {"dump", dump, METH_VARARGS},
  {NULL, NULL}
};


initarraylib(void) {
  Py_InitModule("arraylib", arraylibmethods);
  import_libnumarray();
}