r.coin: Add JSON output support

raster/r.coin/Makefile

@@ -2,7 +2,7 @@ MODULE_TOPDIR = ../..
 
 PGM = r.coin
 
-LIBES = $(RASTERLIB) $(GISLIB)
+LIBES = $(RASTERLIB) $(GISLIB) $(PARSONLIB)
 DEPENDENCIES = $(RASTERDEP) $(GISDEP)
 
 include $(MODULE_TOPDIR)/include/Make/Module.make

raster/r.coin/coin.h

@@ -61,6 +61,7 @@ int collapse(long *, int);
 /* print_coin.c */
 int print_coin(int, int, int);
 
+void print_json(char);
 /* print_hdr.c */
 int print_coin_hdr(int);
 

raster/r.coin/local_proto.h

@@ -40,6 +40,7 @@ int collapse(long *, int);
 /* print_coin.c */
 int print_coin(int, int, int);
 
+void print_json(char);
 /* print_hdr.c */
 int print_coin_hdr(int);
 

raster/r.coin/main.c

@@ -49,7 +49,7 @@ int main(int argc, char *argv[])
         struct Option *map1, *map2, *units;
     } parm;
     struct {
-        struct Flag *w;
+        struct Flag *w, *j;
     } flag;
 
     fill =
@@ -90,6 +90,10 @@ int main(int argc, char *argv[])
     flag.w->key = 'w';
     flag.w->description = _("Wide report, 132 columns (default: 80)");
 
+    flag.j = G_define_flag();
+    flag.j->key = 'j';
+    flag.j->description = _("Generate JSON output");
+
     if (G_parser(argc, argv))
         exit(EXIT_FAILURE);
 
@@ -121,8 +125,13 @@ int main(int argc, char *argv[])
         G_fatal_error(_("Raster map <%s> not found"), map2name);
 
     make_coin();
-    print_coin(*parm.units->answer, flag.w->answer ? 132 : 80, 0);
 
+    if (flag.j->answer) {
+        print_json(*parm.units->answer);
+    }
+    else {
+        print_coin(*parm.units->answer, flag.w->answer ? 132 : 80, 0);
+    }
     remove(dumpname);
     remove(statname);
 

raster/r.coin/print_json.c

@@ -0,0 +1,144 @@
+/****************************************************************************
+ *
+ * MODULE:       r.coin
+ *
+ * AUTHOR(S):    Sumit Chintanwar
+ *
+ * PURPOSE:      Json Output for r.coin
+ *
+ * COPYRIGHT:    (C) 2026 by the GRASS Development Team
+ *
+ *               This program is free software under the GNU General Public
+ *               License (>=v2). Read the file COPYING that comes with GRASS
+ *               for details.
+ *
+ ***************************************************************************/
+
+#include "coin.h"
+#include <grass/gjson.h>
+
+#define F_CTOK(C)    ((double)(C)) / 1000000.0
+#define F_CTOM(C)    F_CTOK(C) * 0.386102158542446
+#define F_CTOA(C)    F_CTOK(C) * 247.105381467165
+#define F_CTOH(C)    F_CTOK(C) * 100.0000
+#define F_CTOP(C, R) ((int)R) ? (double)C / (double)R * 100.0 : 0.0
+
+static const char *get_unit_name(char unit)
+{
+    switch (unit) {
+    case 'c':
+        return "cells";
+    case 'p':
+        return "percent";
+    case 'x':
+        return "percent_of_column";
+    case 'y':
+        return "percent_of_row";
+    case 'a':
+        return "acres";
+    case 'h':
+        return "hectares";
+    case 'k':
+        return "square_kilometers";
+    case 'm':
+        return "square_miles";
+    default:
+        return "unknown";
+    }
+}
+
+void print_json(char unit)
+{
+    int r, c;
+    long cat1, cat2;
+    int idx;
+    char *json_string;
+    long total_count;
+    double total_area;
+    double val;
+    char unit_str[2];
+
+    G_JSON_Value *root_value = G_json_value_init_object();
+    G_JSON_Object *root = G_json_object(root_value);
+
+    G_json_object_set_string(root, "module", "r.coin");
+    G_json_object_set_string(root, "map1", map1name);
+    G_json_object_set_string(root, "map2", map2name);
+
+    G_JSON_Value *unit_info_value = G_json_value_init_object();
+    G_JSON_Object *unit_info = G_json_object(unit_info_value);
+
+    unit_str[0] = unit;
+    unit_str[1] = '\0';
+    G_json_object_set_string(unit_info, "code", unit_str);
+    G_json_object_set_string(unit_info, "name", get_unit_name(unit));
+    G_json_object_set_value(root, "unit", unit_info_value);
+
+    G_JSON_Value *coincidence_array_value = G_json_value_init_array();
+    G_JSON_Array *coincidence_array = G_json_array(coincidence_array_value);
+
+    for (r = 0; r < ncat2; r++) {
+        for (c = 0; c < ncat1; c++) {
+            idx = r * ncat1 + c;
+
+            if (table[idx].count > 0) {
+                cat1 = catlist1[c];
+                cat2 = catlist2[r];
+                Cndex = c;
+                Rndex = r;
+
+                switch (unit) {
+                case 'c':
+                    val = (double)table[idx].count;
+                    break;
+                case 'p':
+                    val = F_CTOP(table[idx].area, window_area);
+                    break;
+                case 'x':
+                    col_total(c, 1, &total_count, &total_area);
+                    val = F_CTOP(table[idx].area, total_area);
+                    break;
+                case 'y':
+                    row_total(r, 1, &total_count, &total_area);
+                    val = F_CTOP(table[idx].area, total_area);
+                    break;
+                case 'a':
+                    val = F_CTOA(table[idx].area);
+                    break;
+                case 'h':
+                    val = F_CTOH(table[idx].area);
+                    break;
+                case 'k':
+                    val = F_CTOK(table[idx].area);
+                    break;
+                case 'm':
+                    val = F_CTOM(table[idx].area);
+                    break;
+                default:
+                    val = (double)table[idx].count;
+                    break;
+                }
+
+                G_JSON_Value *entry_value = G_json_value_init_object();
+                G_JSON_Object *entry = G_json_object(entry_value);
+
+                G_json_object_set_number(entry, "cat1", (double)cat1);
+                G_json_object_set_number(entry, "cat2", (double)cat2);
+                G_json_object_set_number(entry, "count",
+                                         (double)table[idx].count);
+                G_json_object_set_number(entry, "area", table[idx].area);
+                G_json_object_set_number(entry, "value", val);
+
+                G_json_array_append_value(coincidence_array, entry_value);
+            }
+        }
+    }
+
+    G_json_object_set_value(root, "coincidence", coincidence_array_value);
+
+    json_string = G_json_serialize_to_string_pretty(root_value);
+    fprintf(stdout, "%s\n", json_string);
+
+    G_json_free_serialized_string(json_string);
+    G_json_value_free(root_value);
+}