r.profile: add JSON support

raster/r.profile/Makefile

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

raster/r.profile/local_proto.h

@@ -2,16 +2,20 @@
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include <grass/parson.h>
 #include <grass/gis.h>
 #include <grass/raster.h>
 
+enum OutputFormat { PLAIN, JSON };
+
 /* main.c */
 int do_profile(double, double, double, double, int, double, int, int, FILE *,
-               char *, const char *, double);
+               char *, const char *, double, enum OutputFormat, char *,
+               JSON_Array *);
 
 /* read_rast.c */
-int read_rast(double, double, double, int, int, RASTER_MAP_TYPE, FILE *,
-              char *);
+int read_rast(double, double, double, int, int, RASTER_MAP_TYPE, FILE *, char *,
+              enum OutputFormat, char *, JSON_Array *);
 
 /* input.c */
 int input(char *, char *, char *, char *, char *, FILE *);

raster/r.profile/main.c

@@ -8,6 +8,7 @@
  */
 
 #include <stdlib.h>
+#include <grass/parson.h>
 #include <grass/gis.h>
 #include <grass/raster.h>
 #include <grass/glocale.h>
@@ -39,10 +40,13 @@ int main(int argc, char *argv[])
     struct Cell_head window;
     struct {
         struct Option *opt1, *profile, *res, *output, *null_str, *coord_file,
-            *units;
+            *units, *format;
         struct Flag *g, *c, *m;
     } parm;
     struct GModule *module;
+    enum OutputFormat format;
+    JSON_Value *array_value;
+    JSON_Array *array;
 
     G_gisinit(argv[0]);
 
@@ -102,6 +106,9 @@ int main(int argc, char *argv[])
         _("If units are not specified, current project units are used. "
           "Meters are used by default in geographic (latlon) projects.");
 
+    parm.format = G_define_standard_option(G_OPT_F_FORMAT);
+    parm.units->guisection = _("Print");
+
     if (G_parser(argc, argv))
         exit(EXIT_FAILURE);
 
@@ -147,6 +154,15 @@ int main(int argc, char *argv[])
         res = (window.ew_res + window.ns_res) / 2;
     }
 
+    if (strcmp(parm.format->answer, "json") == 0) {
+        format = JSON;
+        array_value = json_value_init_array();
+        array = json_array(array_value);
+    }
+    else {
+        format = PLAIN;
+    }
+
     G_message(_("Using resolution: %g [%s]"), res / factor, unit);
 
     G_begin_distance_calculations();
@@ -177,17 +193,19 @@ int main(int argc, char *argv[])
     data_type = Rast_get_map_type(fd);
     /* Done with file */
 
-    /* Show message giving output format */
-    G_message(_("Output columns:"));
-    if (coords == 1)
-        sprintf(formatbuff,
-                _("Easting, Northing, Along track dist. [%s], Elevation"),
-                unit);
-    else
-        sprintf(formatbuff, _("Along track dist. [%s], Elevation"), unit);
-    if (clr)
-        strcat(formatbuff, _(" RGB color"));
-    G_message("%s", formatbuff);
+    if (format == PLAIN) {
+        /* Show message giving output format */
+        G_message(_("Output columns:"));
+        if (coords == 1)
+            sprintf(formatbuff,
+                    _("Easting, Northing, Along track dist. [%s], Elevation"),
+                    unit);
+        else
+            sprintf(formatbuff, _("Along track dist. [%s], Elevation"), unit);
+        if (clr)
+            strcat(formatbuff, _(" RGB color"));
+        G_message("%s", formatbuff);
+    }
 
     /* Get Profile Start Coords */
     if (parm.coord_file->answer) {
@@ -207,7 +225,7 @@ int main(int argc, char *argv[])
 
             if (havefirst)
                 do_profile(e1, e2, n1, n2, coords, res, fd, data_type, fp,
-                           null_string, unit, factor);
+                           null_string, unit, factor, format, name, array);
             e1 = e2;
             n1 = n2;
             havefirst = TRUE;
@@ -232,7 +250,7 @@ int main(int argc, char *argv[])
 
             /* Get profile info */
             do_profile(e1, e2, n1, n2, coords, res, fd, data_type, fp,
-                       null_string, unit, factor);
+                       null_string, unit, factor, format, name, array);
         }
         else {
             for (i = 0; i <= k - 2; i += 2) {
@@ -246,11 +264,21 @@ int main(int argc, char *argv[])
 
                 /* Get profile info */
                 do_profile(e1, e2, n1, n2, coords, res, fd, data_type, fp,
-                           null_string, unit, factor);
+                           null_string, unit, factor, format, name, array);
             }
         }
     }
 
+    if (format == JSON) {
+        char *serialized_string = json_serialize_to_string_pretty(array_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(array_value);
+    }
+
     Rast_close(fd);
     fclose(fp);
 
@@ -264,7 +292,8 @@ int main(int argc, char *argv[])
 /* Establish parameters */
 int do_profile(double e1, double e2, double n1, double n2, int coords,
                double res, int fd, int data_type, FILE *fp, char *null_string,
-               const char *unit, double factor)
+               const char *unit, double factor, enum OutputFormat format,
+               char *name, JSON_Array *array)
 {
     double rows, cols, LEN;
     double Y, X, k;
@@ -284,7 +313,8 @@ int do_profile(double e1, double e2, double n1, double n2, int coords,
         /* Special case for no movement */
         e = e1;
         n = n1;
-        read_rast(e, n, dist / factor, fd, coords, data_type, fp, null_string);
+        read_rast(e, n, dist / factor, fd, coords, data_type, fp, null_string,
+                  format, name, array);
     }
 
     k = res / hypot(rows, cols);
@@ -303,7 +333,7 @@ int do_profile(double e1, double e2, double n1, double n2, int coords,
         /* SE Quad or due east */
         for (e = e1, n = n1; e < e2 || n > n2; e += X, n -= Y) {
             read_rast(e, n, dist / factor, fd, coords, data_type, fp,
-                      null_string);
+                      null_string, format, name, array);
             /* d+=res; */
             dist += G_distance(e - X, n + Y, e, n);
         }
@@ -313,7 +343,7 @@ int do_profile(double e1, double e2, double n1, double n2, int coords,
         /* NE Quad  or due north */
         for (e = e1, n = n1; e < e2 || n < n2; e += X, n += Y) {
             read_rast(e, n, dist / factor, fd, coords, data_type, fp,
-                      null_string);
+                      null_string, format, name, array);
             /* d+=res; */
             dist += G_distance(e - X, n - Y, e, n);
         }
@@ -323,7 +353,7 @@ int do_profile(double e1, double e2, double n1, double n2, int coords,
         /* SW Quad or due south */
         for (e = e1, n = n1; e > e2 || n > n2; e -= X, n -= Y) {
             read_rast(e, n, dist / factor, fd, coords, data_type, fp,
-                      null_string);
+                      null_string, format, name, array);
             /* d+=res; */
             dist += G_distance(e + X, n + Y, e, n);
         }
@@ -333,7 +363,7 @@ int do_profile(double e1, double e2, double n1, double n2, int coords,
         /* NW Quad  or due west */
         for (e = e1, n = n1; e > e2 || n < n2; e -= X, n += Y) {
             read_rast(e, n, dist / factor, fd, coords, data_type, fp,
-                      null_string);
+                      null_string, format, name, array);
             /* d+=res; */
             dist += G_distance(e + X, n - Y, e, n);
         }

raster/r.profile/r.profile.html

@@ -48,6 +48,8 @@ <h2>OUTPUT FORMAT</h2>
 If the units are not specified, current coordinate reference system's units will be used.
 In case of geographic CRS (latitude/longitude), meters are used as default unit.
 
+Finally, the output from <em>r.info</em> can be output in JSON by passing the <b>format=json</b> option.
+
 <h2>NOTES</h2>
 
 The profile resolution is measured exactly from the supplied end or
@@ -151,6 +153,107 @@ <h3>Extraction of values along profile defined by coordinates (variant 2)</h3>
  4054.027749 73.988029
 </pre></div>
 
+<h3>JSON Output</h3>
+<div class="code"><pre>
+r.profile -g input=elevation coordinates=641712,226095,641546,224138,641546,222048,641049,221186 -c format=json resolution=1000
+</pre></div>
+
+The output looks as follows:
+
+<div class="code"><pre>
+[
+    {
+        "easting": 641712,
+        "northing": 226095,
+        "distance": 0,
+        "elevation": 84.661506652832031,
+        "red": 113,
+        "green": 255,
+        "blue": 0
+    },
+    {
+        "easting": 641627.47980925441,
+        "northing": 225098.57823319823,
+        "distance": 1000.0000000000125,
+        "elevation": 98.179061889648438,
+        "red": 255,
+        "green": 241,
+        "blue": 0
+    },
+    {
+        "easting": 641546,
+        "northing": 224138,
+        "distance": 1964.0277492948007,
+        "elevation": 83.638137817382812,
+        "red": 100,
+        "green": 255,
+        "blue": 0
+    },
+    {
+        "easting": 641546,
+        "northing": 223138,
+        "distance": 2964.0277492948007,
+        "elevation": 89.141029357910156,
+        "red": 169,
+        "green": 255,
+        "blue": 0
+    },
+    {
+        "easting": 641546,
+        "northing": 222138,
+        "distance": 3964.0277492948007,
+        "elevation": 78.497756958007812,
+        "red": 35,
+        "green": 255,
+        "blue": 0
+    },
+    {
+        "easting": 641546,
+        "northing": 222048,
+        "distance": 4054.0277492948007,
+        "elevation": 73.988029479980469,
+        "red": 0,
+        "green": 249,
+        "blue": 17
+    }
+]
+</pre></div>
+
+<h3>Using JSON output with Python for plotting data</h3>
+
+The JSON output makes for ease of integration with popular python data science libraries. For instance, here
+is an example of creating a scatterplot of distance vs elevation with color coding.
+
+<div class="code"><pre>
+import grass.script as gs
+import pandas as pd
+import matplotlib.pyplot as plt
+
+# Run r.profile command
+elevation = gs.read_command(
+    "r.profile",
+    input="elevation",
+    coordinates="641712,226095,641546,224138,641546,222048,641049,221186",
+    format="json",
+    flags="gc"
+)
+
+# Load the JSON data into a dataframe
+df = pd.read_json(elevation)
+
+# Convert the RGB color values to hex format for matplotlib
+df["color"] = df.apply(lambda x: "#{:02x}{:02x}{:02x}".format(int(x["red"]), int(x["green"]), int(x["blue"])), axis=1)
+
+# Create the scatter plot
+plt.figure(figsize=(10, 6))
+plt.scatter(df['distance'], df['elevation'], c=df['color'], marker='o')
+plt.title('Profile of Distance vs. Elevation with Color Coding')
+plt.xlabel('Distance (meters)')
+plt.ylabel('Elevation')
+plt.grid(True)
+plt.show()
+</pre></div>
+
 <h2>SEE ALSO</h2>
 
 <em>