Random Number Generator

Geo · August 2007

I need to somehow come up with a random number generator for a non-malicious purpose. What I'm trying to do is have my program cause an Alcorn McBride 8-Traxx player to play tracks at random based on other input events. Basically, a button push would trigger a play command, but I want to randomly pick what track is to be played. It's not possible to randomly play the tracks on the 8-Traxx box itself...all I can do is send serial strings to tell it what track numbers to play. My only other alternative would be to just call the files in a seemingly random order and hope nobody notices the pattern, which is highly likely as these sound files are quite short and there are not that many of them, and I want it to be truly random anyway.

ericmedley · August 2007

There is a random number generator
This from the help file.

Num = RANDOM_NUMBER(1000) // 0 <= Num < 1000

Then use any of the stock sorts to create a random/unique list of numbers and go from there.

Hope that helps

Joe Hebert · August 2007

You may want to try out the RANDOM_NUMBER function that's built into Netlinx.

Joe Hebert · August 2007

Shuffle This

If you want to play all the tracks in your list randomly and not have any tracks repeat until all tracks are played once then you might find the following code useful.

Compile, download, and then watch nShuffledPlaylist in the debugger. Every time you push button 1 you?ll see the playlist get shuffled.

I?m sure there are different and better ways to shuffle but this is the approach I?ve used in the past.

DEFINE_DEVICE

dvTP	= 10001:1:0

DEFINE_CONSTANT

INTEGER nMaxTracks = 10

DEFINE_VARIABLE

INTEGER nOriginalPlaylist[] = {1,2,3,4,5,6,7,8,9,10}
INTEGER nShuffledPlaylist[] = {1,2,3,4,5,6,7,8,9,10}

INTEGER nNextTrack	//the next track to be played

DEFINE_FUNCTION fnShuffleThis (integer nItems[]) {
      
   INTEGER x		 //looping variable
   INTEGER shufflecount //how many times to shuffle entire list
   INTEGER index	 //current position in the list
   INTEGER rnd		 //random position in the list
   INTEGER temp	 	 //temporary container so swap can be made
   INTEGER len		 //length of list passed in

   len = LENGTH_ARRAY(nItems) 		    //find out how long the list is
   shufflecount = RANDOM_NUMBER(11)+10	    //get a random number between 10-20
   
  
   FOR (x=1; x<=shufflecount; x++) {	    //shuffle the entire list shufflecount times
      FOR (index=1; index<=len; index++) {  //index through the list from start to end
	 rnd = RANDOM_NUMBER(len)+1 	    //generate a random number between 1 and the number of items in list
	 temp = nItems[index]		    //make a copy of the data that is stored at the indexed position
					    //let's make the swap
	 nItems[index] = nItems[rnd]	    //replace the indexed position item with the random positioned item
	 nItems[rnd] = temp		    //take the indexed positioned item and store it in the random position
      }
   }
   
}

DEFINE_FUNCTION fnPlayNextTrack() {

   //Do whatever to play track nShuffledPlaylist[nNextTrack]
   nNextTrack++
   IF (nNextTrack>nMaxTracks) fnResetPlaylist()
}

DEFINE_FUNCTION fnResetPlaylist () {

   nNextTrack = 1
   
   //don't really need this next line, it's only for demo purposes
   //but if you wanted to change the set of tracks to play you could do it here
   nShuffledPlaylist = nOriginalPlaylist

   fnShuffleThis(nShuffledPlaylist)
   
   
}

DEFINE_EVENT

BUTTON_EVENT[dvTP,1] {

   PUSH: {
      fnResetPlaylist()
   }
}

HTH

Geo · August 2007

Thanks

Thanks guys...these did the trick.

Random Number Generator

Comments