r.surf.fractal: Added seed option (#5233)

raster/r.surf.fractal/main.c

@@ -25,9 +25,11 @@ double H; /* Hausdorff-Besickovitch dimension.    */
 int main(int argc, char *argv[])
 {
     struct GModule *module;
-    struct Option *rast_out;   /* Structure for output raster     */
-    struct Option *frac_dim;   /* Fractal dimension of surface.   */
-    struct Option *num_images; /* Number of images to produce.    */
+    struct Option *rast_out;   /* Structure for output raster          */
+    struct Option *frac_dim;   /* Fractal dimension of surface.        */
+    struct Option *num_images; /* Number of images to produce.         */
+    struct Option *seed;       /* Seed for random number generator.    */
+    long seed_value;
 
     G_gisinit(argv[0]); /* Link with GRASS interface.      */
 
@@ -54,9 +56,31 @@ int main(int argc, char *argv[])
     num_images->required = NO;
     num_images->answer = "0";
 
+    seed = G_define_option();
+    seed->key = "seed";
+    seed->type = TYPE_INTEGER;
+    seed->required = NO;
+    seed->label = _("Seed for random number generator");
+    seed->description = _("The same seed can be used to obtain same results"
+                          " or random seed can be generated by other means.");
+
     if (G_parser(argc, argv)) /* Performs the prompting for      */
         exit(EXIT_FAILURE);   /* keyboard input.                 */
 
+    /****** INITIALISE RANDOM NUMBER GENERATOR ******/
+    if (seed->answer) {
+        seed_value = atol(seed->answer);
+        G_srand48(seed_value);
+        G_verbose_message(_("Read random seed from %s option: %ld"), seed->key,
+                          seed_value);
+    }
+    else {
+        /* default as it used to be */
+        seed_value = G_srand48_auto();
+        G_verbose_message(_("Autogenerated random seed set to: %ld"),
+                          seed_value);
+    }
+
     rast_out_name = rast_out->answer;
     sscanf(frac_dim->answer, "%lf", &H);
     H = 3.0 - H;

raster/r.surf.fractal/spec_syn.c

@@ -42,9 +42,6 @@ int specsyn(double *data[2], /* Array holding complex data to transform. */
     double phase, rad, /* polar coordinates of Fourier coeff.  */
         *temp[2];
 
-    /* You can set GRASS_RANDOM_SEED for repeatability */
-    G_math_srand_auto(); /* Reset random number generator.       */
-
     temp[0] = (double *)G_malloc(nn * nn * sizeof(double));
     temp[1] = (double *)G_malloc(nn * nn * sizeof(double));
 

raster/r.surf.fractal/testsuite/test_r_surf_fractal.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+
+"""
+MODULE:    Test of r.surf.fractal
+
+AUTHOR(S): Nishant Bansal <[email protected]>
+
+PURPOSE: Test fractal surface generation of a given fractal dimension.
+
+COPYRIGHT: (C) 2025 by Nishant Bansal and 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.
+"""
+
+import os
+from grass.gunittest.case import TestCase
+from grass.gunittest.main import test
+
+
+class TestRSurfFractal(TestCase):
+    """Test case for r.surf.fractal"""
+
+    # Raster map name to be used as output
+    output = "test_fractal"
+
+    @classmethod
+    def setUpClass(cls):
+        """Set up necessary environment"""
+        # Set up temporary computational region
+        cls.use_temp_region()
+        cls.runModule("g.region", rows=10, cols=10)
+
+    @classmethod
+    def tearDownClass(cls):
+        """Clean up temporary environment"""
+        cls.del_temp_region()
+
+    def tearDown(self):
+        """Remove the output created from the module after each test"""
+        self.runModule("g.remove", flags="f", type="raster", name=[self.output])
+
+    def test_default_settings(self):
+        """Test r.surf.fractal with default settings."""
+        self.assertModule("r.surf.fractal", output=self.output)
+        self.assertRasterExists(self.output, msg="Output Raster not created")
+
+    def test_dimension_number_params(self):
+        """Test r.surf.fractal with the specified dimension and number parameters."""
+        os.environ["GRASS_RANDOM_SEED"] = "42"
+        fractal_dim = 2.0005
+        num_images = 2
+
+        self.assertModule(
+            "r.surf.fractal",
+            dimension=fractal_dim,
+            number=num_images,
+            output=self.output,
+        )
+
+        self.assertRasterExists(self.output, msg="Output Raster not created")
+        self.assertRasterFitsUnivar(
+            self.output,
+            reference={"mean": -3693.824428, "stddev": 12477.543361},
+            precision=1e-6,
+        )
+
+    def test_random_seed_option(self):
+        """Test r.surf.fractal checks whether the random seed option sets a random number."""
+        fractal_dim = 2.0005
+        num_images = 2
+        seed_value = 22
+
+        self.assertModule(
+            "r.surf.fractal",
+            dimension=fractal_dim,
+            number=num_images,
+            seed=seed_value,
+            output=self.output,
+        )
+
+        self.assertRasterExists(self.output, msg="Output was not created")
+        self.assertRasterFitsUnivar(
+            self.output,
+            reference={"mean": -925.148233, "stddev": 19416.071318},
+            precision=1e-6,
+        )
+
+
+if __name__ == "__main__":
+    test()