[vc_row][vc_column width=”1/1″][vc_column_text]Original: http://auzieman.blogspot.com/2012/05/modeling-weighted-random-walk-in-c.html

Here is an experiment I was attempting when working on the linksprite arduino robot kit.  My idea is to make a weighted random walk and while the c++ code worked fairly well (some issues) the robot often got caught in a loop.

To try out this code you should only need a c compiler, I used gcc under linux but honestly this is so simple you shouldn’t need too complicated a setup.  Cygwin under windows or just about any c compiler should do the trick with a little work.

<code>1:   #define _GNU_SOURCE   
2:   #include &lt;stdio.h&gt;   
3:   #include &lt;math.h&gt;   
4:   #include &lt;stdlib.h&gt;   
5:   #include &lt;time.h&gt;   
6:   int x=0;   
7:   int y=0;   
8:   int bias1=50;   
9:   int bias2=30;   
10:   int bias3=25;   
11:   int bias4=30;   
12:   int bias5=55;   
13:   int cnt;   
14:   int xmax=20;   
15:   int ymax=20;   
16:   int xp;   
17:   int yp;   
18:   int dc=0;   
19:   int out;   
20:   int area[20][20];   
21:   int rndm;   
22:   void intloc(){   
23:   xp=ymax/2;   
24:   yp=ymax/2;   
25:   printf("x %u, y %u \n",xp,yp);   
26:   }   
27:   initmap(){   
28:   for ( x=0 ; x &lt; xmax ; x++ ){   
29:   for ( y=0 ; y &lt; ymax ; y++ ){   
30:    area[x][y]=0;   
31:   }   
32:   }   
33:   }   
34:   void printmap(){   
35:   printf("Col \n");    
36:   for ( y=0 ; y &lt; ymax ; y++ ){   
37:   printf("%u ;",y);   
38:   }   
39:   printf("\n");   
40:   for ( x=0 ; x &lt; xmax ; x++ ){   
41:    printf("r %u; ",x);   
42:   for ( y=0 ; y &lt; ymax ; y++ ){   
43:   out=area[x][y];   
44:    printf("%u ;",out);   
45:   }   
46:   printf("\n");   
47:   }   
48:   }   
49:   void updloc(dc){   
50:   if (dc==0){   
51:   }   
52:   }   
53:   void main()   
54:   {   
55:   //randNumber = random(0, 150);   
56:   srand ( time(NULL) );   
57:   rndm=rand() % 150 + 1;   
58:   initmap();   
59:   intloc();   
60:   printmap();   
61:   for (cnt=0; cnt&lt;100;cnt++){   
62:   rndm=rand() % 150 + 1;   
63:   printf("x %u, y %u rand:%u\n",xp,yp,rndm);   
64:   if ((rndm-bias1) &lt;= 10 &amp;&amp; (rndm-bias1) &gt; 0){   
65:   printf("east\n");   
66:   xp--;   
67:   }else if ((rndm-bias2) &lt;= 40 &amp;&amp; (rndm-bias1) &gt; 10){   
68:   printf("west\n");   
69:   xp++;   
70:   }else if ((rndm-bias3) &lt;= 60 &amp;&amp; (rndm-bias1) &gt; 40){   
71:   printf("north\n");  
72:   yp--;   
73:   }else if ((rndm-bias4) &lt;= 70 &amp;&amp; (rndm-bias1) &gt; 60){   
74:   printf("south\n");  
75:   yp++;   
76:   }else if ((rndm-bias5) &lt;= 80 &amp;&amp; (rndm-bias1) &gt; 70){   
77:   printf("north 2\n");   
78:   yp--;  
79:   printf("x %u, y %u rand:%u\n",xp,yp,rndm);   
80:   area[xp][yp]=5;  
81:   yp--;   
82:   }else {   
83:   printf("other\n");   
84:   }  
85:   //update position   
86:   printf("x %u, y %u rand:%u\n",xp,yp,rndm);   
87:   area[xp][yp]=5;   
88:   printmap();   
89:   //printf("Read line of %u characters: %s\n", read, line);    
90:   //printf("Read line of %u characters: %s\n", read, line);    
91:   }   
92:   }   
</code>

To be honest I would love to get this working better, I would love to find a book that actually covers this stuff better. Not just a bunch of formulas but an actual from formula to source code examples.[/vc_column_text][/vc_column][/vc_row]