GRASS Programmer's Manual  6.4.2(2012)
c_point.c
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00001 
00002 /****************************************************************
00003  * I_cluster_point (C,x)
00004  *     struct Cluster *C;
00005  *     DCELL *x;
00006  *
00007  * adds the point x to the list of data points to be "clustered"
00008  *
00009  * returns
00010  *   0  ok
00011  *  -1  out of memory, point not added
00012  *   1  all values are zero, point not added
00013  *
00014  * the dimension of x must agree with the number of bands specified
00015  * in the initializing call to I_cluster_begin()
00016  *
00017  * note: if all values in x are zero, the point is rejected
00018  ***************************************************************/
00019 
00020 #include <grass/cluster.h>
00021 static int extend(struct Cluster *, int);
00022 static int all_zero(struct Cluster *, int);
00023 
00024 int I_cluster_point(struct Cluster *C, DCELL * x)
00025 {
00026     int band;
00027 
00028     /* reject points which contain nulls in one of the bands */
00029     for (band = 0; band < C->nbands; band++)
00030         if (G_is_d_null_value(&x[band]))
00031             return 1;           /* fixed 11/99 Agus Carr */
00032     /*
00033        if (band >= C->nbands)
00034        return 1;
00035      */
00036 
00037     /* extend the arrays for each band, if necessary */
00038     if (!extend(C, 1))
00039         return -1;
00040 
00041     /* add the point to the points arrays */
00042     for (band = 0; band < C->nbands; band++) {
00043         register double z;
00044 
00045         /*       if(G_is_d_null_value(&x[band])) continue; */
00046         z = C->points[band][C->npoints] = x[band];
00047         C->band_sum[band] += z;
00048         C->band_sum2[band] += z * z;
00049     }
00050     C->npoints++;
00051     return 0;
00052 }
00053 
00054 int I_cluster_begin_point_set(struct Cluster *C, int n)
00055 {
00056     return extend(C, n) ? 0 : -1;
00057 }
00058 
00059 int I_cluster_point_part(struct Cluster *C, DCELL x, int band, int n)
00060 {
00061     DCELL tmp = x;
00062 
00063     if (G_is_d_null_value(&tmp))
00064         return 1;
00065     C->points[band][C->npoints + n] = x;
00066     C->band_sum[band] += x;
00067     C->band_sum2[band] += x * x;
00068 
00069     return 0;
00070 }
00071 
00072 int I_cluster_end_point_set(struct Cluster *C, int n)
00073 {
00074     int band;
00075     int cur, next;
00076 
00077     cur = C->npoints;
00078     n += C->npoints;
00079     for (next = cur; next < n; next++) {
00080         if (!all_zero(C, next)) {
00081             if (cur != next)
00082                 for (band = 0; band < C->nbands; band++)
00083                     C->points[band][cur] = C->points[band][next];
00084             cur++;
00085         }
00086     }
00087     return C->npoints = cur;
00088 }
00089 
00090 static int all_zero(struct Cluster *C, int i)
00091 {
00092     int band;
00093 
00094     for (band = 0; band < C->nbands; band++)
00095         if (C->points[band][i])
00096             return 0;
00097     return 1;
00098 }
00099 
00100 static int extend(struct Cluster *C, int n)
00101 {
00102     int band;
00103 
00104     while ((C->npoints + n) > C->np) {
00105         C->np += 128;
00106         for (band = 0; band < C->nbands; band++) {
00107             C->points[band] =
00108                 (DCELL *) I_realloc(C->points[band], C->np * sizeof(DCELL));
00109             if (C->points[band] == NULL)
00110                 return 0;
00111         }
00112     }
00113     return 1;
00114 }
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