natgrid_linear.c

C语言编写的

#include <stdio.h>

/* Function prototype for c_natgrids */
extern float *c_natgrids(int, float [], float [], float [],
                          int, int, float [], float [], int *);

/* Specify number of input data points and the size of the output grid */
#define NUMIN   80732 
#define NUMXOUT 600
#define NUMYOUT 200

/* Specify the range of the input, or type NULL to have the program calculate it */

#define XMAX 167  
#define XMIN 161 
#define YMAX 74
#define YMIN 72

main(int argc, char *argv[])
{

  FILE *in;
  int i, j, k, ier, count=0, nitems, temp;

  float *out, xo[NUMXOUT], yo[NUMYOUT], xc, yc;
  float x[NUMIN], y[NUMIN], z[NUMIN];
  float x_max, x_min, y_max, y_min;

  /* Check if the file argument is present */
  if (!argv[1]) {
     printf( "\nNo input file specified\n" );
     exit(0);
  }

  /* Check if the file exists */
  in=fopen(argv[1],"r");
  if (in == NULL) {
      printf( "\nUnable to open file\n" );
      exit(0);
  } 
  
  /* Read in longitude, latitude, and elevation from file */
  while(1)
  {
    nitems = fscanf(in, "%f\t%f\t%f\n", &x[count], &y[count], &z[count]);
    if (nitems == EOF)
      break;
    count++;

  }
  
  /* Find the x and y range of input */
  if ((XMAX == NULL) || (XMIN == NULL) || (YMAX == NULL) || (YMIN == NULL)) {
    x_max = x[0];
    x_min = x[0];
    y_max = y[0];
    y_min = y[0];
    for (temp=0; temp < count; temp++)  {
      if (x[temp] > x_max) { x_max = x[temp]; }
      if (x[temp] < x_min) { x_min = x[temp]; }
      if (y[temp] > y_max) { y_max = y[temp]; }
      if (y[temp] < y_min) { y_min = y[temp]; }
    }
  }
  if (XMAX != NULL) { x_max = XMAX; }
  if (XMIN != NULL) { x_min = XMIN; }
  if (YMAX != NULL) { y_max = YMAX; }
  if (YMIN != NULL) { y_min = YMIN; }

 
  /* Calculate the x coordinates of the output grid */
  xc = (x_max-x_min)/(NUMXOUT-1);  
  for (i = 0 ; i < NUMXOUT ; i++) {
    xo[i] = i * xc + x_min;
  }

  /* Calculate the y coordinates of the output grid */
  yc = (y_max-y_min)/(NUMYOUT-1); 
  for (j = 0 ; j < NUMYOUT ; j++) {
    yo[j] = j * yc + y_min;
  }
  

  /* Run the natural neighbor function */
  out = c_natgrids(NUMIN, x, y, z, NUMXOUT, NUMYOUT, xo, yo, &ier); 

  /* Check if any errors were encountered by c_natgrids */ 
  if (ier != 0) {
     printf (" Error return from c_natgrids = %d\n",ier);
  }  

  /* Output the results */ 
  for (k = 0; k < NUMXOUT*NUMYOUT; k++) { 
    printf ("%f\n", out[k]); 
  }   

  fclose(in); 

}