r.stats: add JSON output

raster/r.stats/Makefile

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

raster/r.stats/cell_stats.c

@@ -1,9 +1,11 @@
 #include <stdlib.h>
+#include <grass/parson.h>
 #include <grass/glocale.h>
 #include "global.h"
 
 int cell_stats(int fd[], int with_percents, int with_counts, int with_areas,
-               int do_sort, int with_labels, char *fmt)
+               int do_sort, int with_labels, char *fmt,
+               enum OutputFormat format, JSON_Array *root_array)
 {
     CELL **cell;
     int i;
@@ -65,7 +67,7 @@ int cell_stats(int fd[], int with_percents, int with_counts, int with_areas,
 
     sort_cell_stats(do_sort);
     print_cell_stats(fmt, with_percents, with_counts, with_areas, with_labels,
-                     fs);
+                     fs, format, root_array);
     for (i = 0; i < nfiles; i++) {
         G_free(cell[i]);
     }

raster/r.stats/global.h

@@ -1,10 +1,13 @@
 #include <grass/gis.h>
 #include <grass/raster.h>
+#include <grass/parson.h>
 
 #define SORT_DEFAULT 0
 #define SORT_ASC     1
 #define SORT_DESC    2
 
+enum OutputFormat { PLAIN, JSON };
+
 extern char *no_data_str;
 extern int nfiles;
 extern int nrows;
@@ -19,10 +22,11 @@ extern char *fs;
 extern struct Categories *labels;
 
 /* cell_stats.c */
-int cell_stats(int[], int, int, int, int, int, char *);
+int cell_stats(int[], int, int, int, int, int, char *, enum OutputFormat,
+               JSON_Array *);
 
 /* raw_stats.c */
-int raw_stats(int[], int, int, int);
+int raw_stats(int[], int, int, int, enum OutputFormat, JSON_Array *);
 
 /* stats.c */
 int initialize_cell_stats(int);
@@ -33,4 +37,5 @@ void reset_null_vals(CELL *, int);
 int update_cell_stats(CELL **, int, double);
 int sort_cell_stats(int);
 int print_node_count(void);
-int print_cell_stats(char *, int, int, int, int, char *);
+int print_cell_stats(char *, int, int, int, int, char *, enum OutputFormat,
+                     JSON_Array *);

raster/r.stats/main.c

@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <grass/parson.h>
 #include <grass/glocale.h>
 
 #include "global.h"
@@ -56,6 +57,10 @@ int main(int argc, char *argv[])
     int with_labels;
     int do_sort;
 
+    enum OutputFormat format;
+    JSON_Array *root_array;
+    JSON_Value *root_value;
+
     /* printf format */
     char fmt[20];
     int dp;
@@ -95,6 +100,7 @@ int main(int argc, char *argv[])
                                   explicit fp ranges in cats or when the map
                                   is int, nsteps is ignored */
         struct Option *sort;   /* sort by cell counts */
+        struct Option *format;
     } option;
 
     G_gisinit(argv[0]);
@@ -145,6 +151,9 @@ int main(int argc, char *argv[])
                _("Sort by cell counts in descending order"));
     option.sort->guisection = _("Formatting");
 
+    option.format = G_define_standard_option(G_OPT_F_FORMAT);
+    option.format->guisection = _("Print");
+
     /* Define the different flags */
 
     flag.a = G_define_flag();
@@ -233,6 +242,16 @@ int main(int argc, char *argv[])
                   option.nsteps->key, option.nsteps->key);
         nsteps = 255;
     }
+
+    if (strcmp(option.format->answer, "json") == 0) {
+        format = JSON;
+        root_value = json_value_init_array();
+        root_array = json_array(root_value);
+    }
+    else {
+        format = PLAIN;
+    }
+
     cat_ranges = flag.C->answer;
 
     averaged = flag.A->answer;
@@ -376,10 +395,22 @@ int main(int argc, char *argv[])
         sprintf(fmt, "%%.%dlf", dp);
 
     if (raw_data)
-        raw_stats(fd, with_coordinates, with_xy, with_labels);
+        raw_stats(fd, with_coordinates, with_xy, with_labels, format,
+                  root_array);
     else
         cell_stats(fd, with_percents, with_counts, with_areas, do_sort,
-                   with_labels, fmt);
+                   with_labels, fmt, format, root_array);
+
+    if (format == JSON) {
+        char *serialized_string = NULL;
+        serialized_string = json_serialize_to_string_pretty(root_value);
+        if (serialized_string == NULL) {
+            G_fatal_error(_("Failed to initialize pretty JSON string."));
+        }
+        puts(serialized_string);
+        json_free_serialized_string(serialized_string);
+        json_value_free(root_value);
+    }
 
     exit(EXIT_SUCCESS);
 }

raster/r.stats/r.stats.html

@@ -164,6 +164,73 @@ <h3>Report sorted area intervals of floating-point raster map</h3>
 55.578793-65.6539       760000.000000
 </pre></div>
 
+<h3>JSON Format</h3>
+
+<div class="code"><pre>
+g.region raster=elevation
+r.stats -an input=elevation nsteps=10 sort=desc format=json
+</pre></div>
+
+<div class="code"><pre>
+[
+    {
+        "categories": [
+            {
+                "range": {
+                    "low": 116.02943572998046,
+                    "high": 126.10454292297364
+                }
+            }
+        ],
+        "area": 1188100
+    },
+    {
+        "categories": [
+            {
+                "range": {
+                    "low": 105.9543285369873,
+                    "high": 116.02943572998046
+                }
+            }
+        ],
+        "area": 857300
+    },
+    {
+        "categories": [
+            {
+                "range": {
+                    "low": 126.10454292297364,
+                    "high": 136.17965011596681
+                }
+            }
+        ],
+        "area": 504700
+    },
+    {
+        "categories": [
+            {
+                "range": {
+                    "low": 95.879221343994146,
+                    "high": 105.9543285369873
+                }
+            }
+        ],
+        "area": 336900
+    },
+    {
+        "categories": [
+            {
+                "range": {
+                    "low": 85.804114151000974,
+                    "high": 95.879221343994146
+                }
+            }
+        ],
+        "area": 66500
+    }
+]
+</pre></div>
+
 <h3>Report raster cell counts in multiple raster maps</h3>
 
 Report raster cell counts of landuse and geological categories within