Use a better PRNG for generating the initial weights and the evolution

README.md

@@ -9,6 +9,9 @@ _This is an experiment to see if genetic algorithms can be used to evolve a neur
 * [GoGui](https://github.com/Remi-Coulom/gogui)
 * gcc
 * make
+* [pcg-random](https://www.pcg-random.org/using-pcg-c.html)
+  * Add path for the library to `LIBRARY_PATH`
+  * Add path to header file to `CPATH`
 
 ## TODO
 
@@ -24,4 +27,4 @@ WHITE="./engine/evo"
 REFEREE="gnugo --mode gtp"
 TWOGTP="gogui-twogtp -black \"$BLACK\" -white \"$WHITE\" -referee \"$REFEREE\" -games 10 -size 9 -alternate -sgffile evo"
 gogui -size 9 -program "$TWOGTP" -computer-both -auto
-```
+```

engine/Makefile

@@ -1,5 +1,5 @@
 CFLAGS = -Wall -Wshadow -O3 -g -march=native
-LDLIBS = -lm
+LDLIBS = -lm -lpcg_random
 
 OBJS = brown.o gtp.o genann.o generate_move.o interface.o
 

engine/main.c

@@ -38,7 +38,9 @@
 
 #include "interface.h"
 
+pcg32_random_t rng;
+
 int main(int argc, char **argv) {
-  srand(time(NULL));
+  pcg32_srandom(time(NULL), (intptr_t)&rng);
   boot(argc, argv);
 }

engine/test.c

@@ -258,8 +258,6 @@ int main(int argc, char *argv[])
 {
     printf("GENANN TEST SUITE\n");
 
-    srand(100); //Repeatable test results.
-
     lrun("basic", basic);
     lrun("xor", xor);
     lrun("backprop", backprop);

evolve/Makefile

@@ -1,5 +1,5 @@
 CFLAGS = -Wall -Wshadow -O3 -g -march=native
-LDLIBS = -lm
+LDLIBS = -lm -lpcg_random
 
 OBJS = genann.o evolve.o
 

evolve/evolve.c

@@ -24,18 +24,18 @@ SOFTWARE.
 
 */
 
+#include <pcg_variants.h>
 #include <math.h>
 #include <stdbool.h>
 #include <stdlib.h>
-#include <sys/time.h>
+#include <time.h>
 
 #include "evolve.h"
 
+pcg32_random_t rng;
+
 void seed() {
-  struct timeval tp;
-  gettimeofday(&tp, NULL);
-  unsigned seed = (unsigned)tp.tv_usec;
-  srand(seed);
+  pcg32_srandom(time(NULL), (intptr_t)&rng);
 }
 
 genann **load_nns(char *ann1_name, char *ann2_name) {
@@ -83,26 +83,18 @@ void check_nns(genann **nns) {
   printf("Sanity check passed\n");
 }
 
-double prng() {
-  return GENANN_RANDOM();
-}
-
 genann *child_from_cross_over(genann **nns) {
   printf("Cross over\n");
   // Pick order in which to use the NNs
-  int i = (GENANN_RANDOM() > 0.5 ? 0 : 1);
+  int i = pcg32_boundedrand(2);
   genann *first_parent = nns[i];
   genann *second_parent = nns[(i+1) % 2];
   // Find weight at which to cross over
-  int cross_over_point = pick_point(first_parent, prng);
+  int cross_over_point = pcg32_boundedrand(first_parent->total_weights);
   // Do the cross over
   return cross_over(first_parent, second_parent, cross_over_point);
 }
 
-int pick_point(genann *nn, double (*prng)()) {
-  return rintf(floor(prng() * nn->total_weights));
-}
-
 genann *cross_over(genann *first_parent, genann *second_parent, int cross_over_point) {
   genann *child = genann_copy(first_parent);
   for (int ci = cross_over_point; ci < first_parent->total_weights; ci++) {
@@ -114,9 +106,9 @@ genann *cross_over(genann *first_parent, genann *second_parent, int cross_over_p
 genann *child_from_mutation(genann **nns) {
   printf("Mutation\n");
   // Pick a NN to use
-  genann *parent = nns[GENANN_RANDOM() > 0.5 ? 0 : 1];
+  genann *parent = nns[pcg32_boundedrand(2)];
   // Find weight to mutate
-  int mutation_point = pick_point(parent, prng);
+  int mutation_point = pcg32_boundedrand(parent->total_weights);
   // Mutate the weight
   return mutate(parent, mutation_point);
 }

evolve/evolve.h

@@ -24,13 +24,16 @@ SOFTWARE.
 
 */
 
+#include <pcg_variants.h>
+
 #include "genann.h"
 
+extern pcg32_random_t rng;
+
 void seed();
 genann **load_nns(char *ann1_name, char *ann2_name);
 void check_nns(genann **nns);
 genann *child_from_cross_over(genann **nns);
 genann *child_from_mutation(genann **nns);
 genann *cross_over(genann *first_parent, genann *second_parent, int cross_over_point);
 genann *mutate(genann *parent, int mutation_point);
-int pick_point(genann *nn, double (*prng)());

evolve/test.c

@@ -32,17 +32,6 @@ double returns_point_one() { return 0.1; }
 double returns_point_nine_nine() { return 0.99; }
 double returns_point_seven() { return 0.7; }
 
-void test_pick_point() {
-  genann *nn = genann_init(1, 1, 1, 1);
-  lequal(nn->total_weights, 4);
-  // Allowed values: 0 1 2 3
-
-  lequal(pick_point(nn, returns_point_one), 0);
-  lequal(pick_point(nn, returns_point_three), 1);
-  lequal(pick_point(nn, returns_point_seven), 2);
-  lequal(pick_point(nn, returns_point_nine_nine), 3);
-}
-
 void test_cross_over() {
   genann *nn1 = genann_init(1, 1, 1, 1);
   genann *nn2 = genann_init(1, 1, 1, 1);
@@ -67,7 +56,6 @@ void test_mutate() {
 int main(int argc, char **argv) {
   printf("Evolve test suite\n");
 
-  lrun("pick_point", test_pick_point);
   lrun("cross_over", test_cross_over);
   lrun("mutate", test_mutate);
 }

initial-population/Makefile

@@ -1,5 +1,5 @@
 CFLAGS = -Wall -Wshadow -O3 -g -march=native
-LDLIBS = -lm
+LDLIBS = -lm -lpcg_random
 
 OBJS = genann.o
 

initial-population/main.c

@@ -29,8 +29,10 @@ SOFTWARE.
 
 #include "genann.h"
 
+pcg32_random_t rng;
+
 int main(int argc, char **argv) {
-  srand(time(NULL));
+  pcg32_srandom(time(NULL), (intptr_t)&rng);
 
   // Do not buffer stdout
   setbuf(stdout, NULL);

lib/genann.h

@@ -28,16 +28,15 @@
 #define GENANN_H
 
 #include <stdio.h>
+#include <pcg_variants.h>
+
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#ifndef GENANN_RANDOM
-/* We use the following for uniform random numbers between 0 and 1.
- * If you have a better function, redefine this macro. */
-#define GENANN_RANDOM() (((double)rand())/RAND_MAX)
-#endif
+// As suggested by the pcg-random library
+#define GENANN_RANDOM() (ldexp(pcg32_random(), -32))
 
 struct genann;