1 files changed, 130 insertions, 0 deletions
diff --git a/src/markov.h b/src/markov.h
new file mode 100644
index 0000000..052af53
--- /dev/null
+++ b/src/markov.h
@@ -0,0 +1,130 @@
+#ifndef MARKOV_H
+#define MARKOV_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include <time.h>
+
+extern int ITEMS;
+extern double chain[][ITEM_CAP];
+extern char item_names[][64];
+
+void generate_chain(char *file_path)
+{
+    FILE *fp = fopen(file_path, "r");
+    if(!fp) {
+        fprintf(stderr, "ERROR: Could not open file %s\n", file_path);
+        exit(EXIT_FAILURE);
+    }
+
+    int items_seen[ITEM_CAP][ITEM_CAP] = {0};
+    int cur_item = -1;
+
+    char line[256] = {0};
+    while((fgets(line, sizeof(line), fp)) != NULL)
+    {
+        if(line[strlen(line)-1] == '\n')
+            line[strlen(line)-1] = '\0';
+
+        int item = ITEMS;
+
+        for(int i = 0; i < ITEMS; i++)
+        {
+            if(strcmp(line, item_names[i]) == 0)
+                item = i;
+        }
+
+        if(item == ITEMS) {
+            ITEMS++;
+            strcpy(item_names[item], line);
+        }
+
+        if(cur_item != -1)
+            items_seen[cur_item][item]++;
+
+        cur_item = item;
+    }
+
+    fclose(fp);
+
+    for(int i = 0; i < ITEMS; i++)
+    {
+        int all = 0;
+        for(int j = 0; j < ITEMS; j++)
+            all += items_seen[i][j];
+
+        for(int j = 0; j < ITEMS; j++)
+            chain[i][j] = (double)items_seen[i][j]/all;
+    }
+}
+
+int walk_step(int item)
+{
+    int item_lim = 0;
+    int r = rand();
+
+    for(int i = 0; i < ITEMS; i++)
+    {
+        item_lim += RAND_MAX * chain[item][i];
+        if(r <= item_lim) return i;
+    }
+
+    return -1;
+}
+
+void take_walk()
+{
+#ifdef SAVE_TO_FILE_ON_WALK
+    FILE *fp = fopen(SAVE_TO_FILE_ON_WALK, "w");
+    if(!fp) {
+        fprintf(stderr, "ERROR: Could not open file %s\n", SAVE_TO_FILE_ON_WALK);
+        exit(EXIT_FAILURE);
+    }
+#endif
+
+    int items_seen[ITEM_CAP] = {0};
+    int cur_item = rand() % ITEMS;
+
+    for(size_t i = 0; i < WALK_LEN; i++)
+    {
+    #ifdef PRINT_ON_WALK
+        puts(item_names[cur_item]);
+    #endif
+    #ifdef SAVE_TO_FILE_ON_WALK
+        fprintf(fp, "%s\n", item_names[cur_item]);
+    #endif
+        items_seen[cur_item]++;
+        int ni = walk_step(cur_item);
+        assert(ni != -1);
+        cur_item = ni;
+    }
+
+#ifdef SAVE_TO_FILE_ON_WALK
+    fclose(fp);
+    printf("Saved file with %d items at %s\n", WALK_LEN, SAVE_TO_FILE_ON_WALK);
+#endif
+
+#ifdef PRINT_ITEM_FREQUENCY
+    puts("Item Frequency:");
+    for(int i = 0; i < ITEMS; i++)
+        printf("%f %s\n", (double)items_seen[i]/WALK_LEN, item_names[i]);
+    puts("");
+#endif
+}
+
+void print_chain()
+{
+    puts("Chain Matrix:");
+    for(int i = 0; i < ITEMS; i++)
+    {
+        printf("{");
+        for(int j = 0; j < ITEMS; j++)
+            printf(" %f,", chain[i][j]);
+        printf("}\n");
+    }
+    puts("");
+}
+
+#endif