[Resolved] How to make banners show more often than others?

[bodzan]

I have this banner system that randomly shows banners stored in the database...

It is pretty straight forward to anyone who knows how to do it...

However, I want to be able to make banners show in different manner depending on a advertiser (i.e. the amount of money he/she invested in the project).

To be exact:
I want to have, say, 3 groups of advertisers
1. people that pay $xxx
2. people that pay $xx
3. people that pay $x

Banners of the group 1 should be the ones who are shown more often than others. Those of group 2 little less often and those of the group 3 rarely.

I hope you can understand what I need here.

My randomizer function is like this:

srand((double)microtime()*1000000);
$randrow = @rand(0,$num_rows-1);
mysql_data_seek($result,$randrow);

I'm really stumped on this and I would like some pointers. Thanks in advance on any help...

Tell me if I didn't made much sense in explaining this and if I should explain more...

[jkurrle]

I'm not going to propose any code, but I will throw in a little logic here. Let's look at your example. You have 3 groups:

Group_1: which is the low paying group. Let's give them a base value of 1.

Group_2: the second group. Let's say we'll show their banners 3 times more than Group_1. So their value is 3.

Group_3: Your high dollar group. Let's say we'll show their banners 6 times more than Group_1. So their value is 6.

Adding values together you have 1+3+6=10 total banner placements.

Using your rand() function, you could take a random number between zero and 1. Take that number times ten and use a function like ceil() to round it up to a whole number. Then if the number is 1, display Group_1's banner. If the number is 2-4, display Group_2's banner. Finally if the number is 5-10, display Group_3's banner.

Does this make sense?

[gfoot]

Ignoring your groups for a moment, one way to pick random elements favouring some over others is to think of it like a raffle, where some people buy more tickets than others. Each element which might be picked gets a score, which is a number of entries into the raffle. Make an empty array, then loop through your potential elements putting a number of copies of each into the array. Then take a random entry from the array, and use the banner it refers to.

Don't do this with high scores, it's not efficient! If you want to do it efficiently, you can expand the algorithm to just use numbers rather than actually filling in the array:

1. Add up the total score of all elements

2. Pick a number from 0 up to the total score minus one

3. Loop over all the elements again, accumulating their scores, until you go strictly greater than the random value chosen

4. At this point, the element you just processed is the "chosen one"
   [/list=1]

[bodzan]

To jkurrle:

I think that you ridea makes perfect sense...

Also I think that it is so cool! I think I just might be doing it your way!

I thought that I should be doing this using some math formula of some sort but this idea of yours is so neat that I love it...

I'll let you know whether it works O.K...

To gfoot:
I have to say I'm a bit confused with your answer... I am not familiar with "raffle" so i don't know what you are getting at with it...

Also: did you mean that I should take say 3 copies of an item (if it is scored 3) into the array and it will have bigger chance to be present in the random selection of an array? If so: I like it!

So the logic would be:
1. group has 1 point
2. group has 2 points
3. group has 3 points

The array which I'll be forming would consist of 1 copy of the each item that belongs to group 1, 2 copies of each item of group 2 and 3 copies of each item from group 3... This way surely the items from the group 3 would have more than overwhelming majority and therefore would be shown more often that those from group 2 or 1...

Did I get it right gfoot?

Am I getting you gfoot right?

[gfoot]

bodzan, yes, that's right. A "raffle" is just a kind of lottery - people buy tickets, if you pay more you get more tickets, and one ticket is drawn at random and the owner of the ticket gets a prize.

If you found jkurrle's answer clearer then that's cool, we're talking about the same thing.

Be careful if you do decide to just put lots of entries into an array and pick one at random though - as I said, that's inefficient because you're going to end up with a big array if you have a lot of banners or if some banners have quite high scores. Doing it by calculating the total score isn't too hard - it's what jkurrle did in his email for the case of having just one banner in each group. If you're still confused by it then I can post code to do it.

[bodzan]

Thanx again gfoot...

Well, well - I'm not so slow after all 😃...

I'm glad I understood what you meant... And so far I think I might try either but you're right it might be little more time consuming if I have more than 50 or so banners but luckilly I don't have that amount just yet...

Either way, I figured it doing it like this:
In the array I will have only id's of the banner's since they are all in the database and the array would be like 1,1,1 2,3,3,4,4,4 and so on... Of course, 1 (in this array) is banner of group 3 and 2 is of group 1 and 3 of group 2... So in the end whichever is picked I just show banner with that id...

Does that makes sense? And to tell you the truth this doesn't seem time consuming no matter how many banners are there, is it?

I don't really need the code at the moment but I figure that I just might want to try it for myself and if it works like I think it would might just post the whole code in the Code Library of the PHPBuilder's site... If I do that I'll encourage you to check it out since you are the engineer and you might have better idea of doing it...

[wmhop]

I created this small script based on the logic that jkurrie shared. Or at least the way I understood it. This script echo's the number that was generated along with text describing the cost of the banner.

<?php
$x=mt_rand(1,10);
switch ($x) {
case $x==1:
echo $x." low cost banner <br />";
break;
case ($x>=2 and $x<=4):
echo $x." medium cost banner <br />";
break;
case ($x>=5 and $x<=10):
echo $x." high cost banner <br />";
break;
}
echo "all done!!";
?>

I put this script inside of a for loop that looped 100 times. I ran it 3 times and the results were

"high cost banner" 57 times
"medium cost banner" 33 times
"low cost banner" 10 times

"high cost banner" 67 times
"medium cost banner" 26 times
"low cost banner" 7 times

"high cost banner" 66 times
"medium cost banner" 27 times
"low cost banner" 8 times

I did this more as an exercise for myself but I hope it can help you as well.

After re reading your post this may not be exactly what you want. But maybe it'll help someone else.

[bodzan]

wmhop thank you for the snippet, but I guess I knew that after jkurrle's cool explanation, but thank you either way...

Someone might find it useful though...

[jkurrle]

If you intend to classify your banners into groups, here's a little more food for thought:

Do you intend for each additional group as a whole to be a multiple of hits over Group_1? Or do you want each member of the group to be the same multiple of hits over a member of Group_1? Let me give you an example.

Group_3 from our previous example has 2 banners in it, while Group_1 has 10. Assuming only Group_3 and Group_1 have banners, let's look at what happens roughly with 700 hits:

If Group_3 is given a hits as a whole, Group_3 is given 600 hits, while Group_1 gets 100 hits. Therefore, each banner of Group3 gets 300 hits, while each member of Group_1 gets 10 hits. What happens if 8 members of Group_1 want more exposure and move to Group_3? Then each member of Group_3 gets 60 hits, while your two remaining members of Group_1 get 50. Doesn't seem fair, does it?

If each member of Group_3 is guaranteed 6 times the hits of a member of Group_1, then the math breaks down much differently. Basicly, you'd have 700/(2*6+10) impressions to allocate to each user. Each Group_1 user would get this number of impressions (approximately 32 impressions). Each Group 6 would get approximately 6 times more (approximately 190).

If the numbers skewed so that there were 10 banners in Group_3 and 2 banners in Group_1, the math looks like 700/(10*6+2) impressions (approximately 11.3). Then each user in Group_1 would get 11 impressions and each user in Group_3 would get 68 impressions.

This makes your coding a little more complicated, but more fair to whomever is paying you to host the banners...

[bodzan]

Never thought of it that way...

You made a very good point there
jkurrle, but how would I go coding something like that?

Basically the trouble if I understand it correctly is like this:

unknown_number_of_showings / (unknown_number_of_banners_in_group_1*6 + unknown_number_of_banners_in_group_3)

But let's contemplate about gfoot's example for a moment:
You said there are 2 members of Group 1 (with id's 1 and 2) that has 6 times more exposure than group 3 that has 10 members (id's 3-12). Right?
That makes the array gfoot suggested something like this:
1,1,1,1,1,1,2,2,2,2,2,2,3,4,5,6,7,8,9,10,11,12
Right?

So basically what you suggest when users that have banners with id 3,4,5,6,7,8,9,10 move to a group 1 the array would look like this:

1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4, 5,5,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,8,8,8,8,8,8, 9,9,9,9,9,9,9,10,10,10,10,10,10,11,12

What it seems to me this far the exposure is in this system by far greater in group 1 than it is in group 3... I don't know how to calculate this but I can't seem to get to calculate the point you mentioned either because there are too many unknowns...

So I guess my question now would be which of the two is fairer?

[jkurrle]

Sorry it's taking me so long to get back here. Real life has a nasty tendancy to intrude on programming life. 🙂 Handling the calculations aren't too bad, since the server is doing the calculating. Let's consider how to design such a system though.

First, I must warn you that I am a newbie, and I have been told on this forum once already that my coding is inefficient. Since my experience is limited to what I've already done (not alot), my design is going to be a little awkward. Still, I'll try to be clear with what I'm doing, and you can figure out how to program it more efficiently.

I am comfortable with MySQL, so I would set up a database with a few tables. They would be something like this:

Group_Table:
Group_Number - AutoIncrementing indexed column. Primary sort key.
Group_Description - How you intend to call this group (your "human" name)
Group_Multiplier - What multiplier of the base you are going to use for this group (Group_1 would be 1, of course)
Group_Price - What price you are going to charge this person, based on monthly fee or impression
Group_Price_Method - Choice of Monthly or Impression

This first table gives you the flexibility to set preferred price structures for long term advertisers, or "teaser rates", and allows for flexible billing.

Banner_Table:
Banner_Number - AutoIncrementing indexed column. Primary sort key.
Banner_Group - link to Group_Number for what type of group it is.
Banner_Description - "Real World" description of the banner
Banner_Location - Url reference of where the banner is located
Banner_Hits - number of hits the banner has received.

Finally, I would likely make a small table with the following information:

Banner_Totals:
Group_Number - References back to Group_Number in the Group_Table table
Group_Amount - the number of banners in this type of Group

While you could likely get this information with a query against the Banner_Table, this might be a faster way of pulling your information.

At this point, I would likely build a banner management page and a group management page to add, change, move, delete and join groups and banners. Once I had this done, I'd then concentrate on the bread and butter of the problem.

Once again, real life intrudes. I'll write more a little later.

[jkurrle]

Errata from previous post: Add a Banner_Link column to your Banner_Table table. This is the URL that you go to when you click on the banner.

Now, as for the bread and butter. We already know the basic algorithm for the assigment of advertising space. But how do we know exactly what banner to assign to each instance. This is where the fun begins.

I would create a one entry table with the base number of our calculations. This number would be calculated as you add/remove a banner. That would likely be the fastest method, instead of doing a lot looping through a while loop, reading records and calculating. Your base number would be based on the following:

$basenum=Group_1:MultiplierNumberOfBanners + Group_2:MultiplierNumberOfBanners + ...

Next, we need to establish some break points between the groups. Something like this:

Breakpoint_1=basenumGroup_1:MultiplierNumberOfBanners
Breakpoint_2=Breakpoint_1+basenumGroup_2:MultiplierNumberOfBanners
and so on...

We might actually be calculating this later in the program, but this is a step we will use.

Now to the meat of the problem:

// make your database connection already...

//This picks from random what banner to display, based on the 
// $basenum times the random number, rounded up to the next 
// integer.
$random="0"
// The next loop makes sure the random number that's generated
// isn't zero
while ($random="0")
  {
  $first_step=rand(0,1);
  $second_step=$basenum*$first_step;
  $random=ceil($second_step);
  }

// $step will be used to identify the banner when it becomes
// equal to or greater than $random
$step="0";
// $Found_It will be used to break out of a while loop, once the
// correct banner is found
$Found_It="No";

// Get array of group numbers correlated to how many banners
// are in the group
$query="select * from Banner_Totals";
$result=mysql_query($query)
  or die("Select from Banner_Totals had errors(1)");

// This will do some useless thrashing after the result is found,
// but I don't know how to get around it...
while ($row=mysql_fetch_array($result,MYSQL_ASSOC))
  {
  extract($row);

  // we need the Group_Multiplier to take the correct sized steps
  // in a procedure below...
  $query="select Group_Multiplier from Group_Table 
    where Group_Number='$Group_Number' ";
  $result=mysql_query($query)
    or die("Select from Group_Table had errors(2)");
  $row=mysql_fetch_array($result);
  extract($row);

  // Initialize the count before we process a Group type
  $count="0";
  // Now we process this loop until we find the correct banner
  // or we exhaust this group type
  while (($count < $Group_Amount) && ($Found_It="No"))
    {
    // we add the Group_Multiplier to step to increase the count
    // appropriately.  This is the "tricky logic" of the piece.
    $step=$step+$Group_Multiplier;
    // once $step is greater than or equals $random, we have 
    // found the banner to display
    if ($step>=$random)
      $Found_It="Yes";
    // even after the banner is found, we still need to increment
    // the banner group counter by one, so we get the correct 
    // banner later on to display.
    $count=$count+"1";
    }
  }

// I'm sure there's a more efficient way to do this, but I can't think
// of it right now...
$query="select * from Banner_Table
  where Banner_Group='$Group_Number' ";
$result=mysql_query($query)
  or die("Select from Banner_Table had errors(3)");
// here, it gets cheesy, but I don't know enough to get around it
$banner_count="0";
while ($banner_count<>$count)
  {
  $row=mysql_fetch_array($result,MYSQL_ASSOC);
  $banner_count=$banner_count+"1";
  }
//finally we have our banner, so we extract all the data about it.
extract($row);

// Now we know what Banner to display, so we display it...
echo "<a href='$Banner_Link' target='new'>$Banner_Location</a>";

// Then we add one to its hit count...
$Banner_Hits=$Banner_Hits+"1";
$query="update Banner_Table set
  Banner_Hits='$Banner_Hits' 
  where Banner_Number='$Banner_Number' ";
$result=mysql_query($query)
  or die("Update into Banner_Table had errors");

This code is far from perfect. I wrote this from the top of my head, so I'm sure there are structural errors here and there and it is far from efficient code. Still, this will give you an idea of how you might build a banner display structure based on the rules we worked out in a previous post.

Take this code and examine it thoroughly. There may be logic errors or programming errors in it. I haven't had time to proof it. I give no warranty to how well it will work...

[jkurrle]

Bodzan, you pretty much understand the math of a weighted banner system, so I will address another aspect of your post. You were wondering what would be a "fair" system to deploy. By looking at the previous examples I gave, it should become more obvious.

In the first example, we weighted one group as a whole over a second group. Because we weighted the percentage of impressions against a group, instead of individuals, we ended up with ratios of "impressions" to "money paid" that skewed all over, based on group membership. The more people that are in a specific group, the more it dilutes their chances of getting a fair share of impressions.

In the second example, we more closely approach the "raffle" idea espoused by gfoot. Each person is given a "weighted" percentage of the pot, based on what they paid. The person who pays more is guaranteed to have a specificly defined larger ratio/multiple of impressions, versus a person who pays less. Anyone who pays the same as him gets the same amount of impressions.

Maintaining that unchanging ratio from payee to payee is what makes a "fair" system. If I pay to have my banners displayed 3 times more than the cheaper guy, that's what I expect to see. If someone pays the same as me, I expect to have the same number of impressions as they do. As a customer, that would be my concept of "fair". And that is exactly what the second system does.

Does this make more sense?

[bodzan]

Thanks a lot guys...

I guess gfoot was right all along and his system is the best way to go in order to be fair to advertizers...

But to be quite fair jkurrle's elaboration made it clear why...

The programming part is quite unfinished by my part so I'll keep this thread open untill I get all issues resolved and I hope to be able to provide visitors of this forum some finishing code that recaps all mentioned...

Wmhop gave a pretty nice looking snippet to get everyone started, but I want to keep it fair to advertizers so I'll go the other way...

Well, this was one nice discussion on this forum...

Hope that someone's helped with this...

[jkurrle]

Bodzan, I thought I'd add an idea for a testing mechanism for you. Once you create your banner code and have some banners set in your database/array, place the code in a test page with the following line of html code at the bottom:

<meta http-equiv='refresh' content=0;url=''>

open your browser to this page and leave it run for a while. The page will continually refresh and reload the banner code. To kill it, simply close the browser window. Then, you can look at your hit counts to see how accurately your code is representing your banner clients.

Of course, the more banners you put in the various groups, the longer you should run your test page to get a more accurate view of how your code is performing. The more hits you generate, the more the distribution is going to line up with the math, despite the random element.

[bodzan]

And it works great so far...

What I did is made a table in my database with following fields:

bID (int, autoincrement)| client (varchar)| url (varchar) | shows (int)| clicks (int)| file (blob)| fileType (varchar)| multiplier set('0','1','2','3','4','5','6','7','8','9','10', '11','12','13','14','15')| dateAdded (date)

Clearly, I made a system for uploading banners and regulating these data...
This should be all straightforward for now.

Then I made and banner functions page like this:

function showBanner(){

$sql = my_query("SELECT * FROM banners WHERE multiplier != '0'");

$niz = Array();
while($r = mysql_fetch_assoc($sql)){
	$i=0;
	while($i<$r['multiplier']){
		$niz[] = $r['bID'];
		$i++;
	}
}
$a = array_rand($niz);

echo "<a href=\"click.php?id=".$niz[$a]."\" target=\"_blank\"><img src=\"getfile.php?id=".$niz[$a]."\" border=\"0\" height=\"75\" width=\"255\"></a>";
$sqlu = my_query("UPDATE banners SET shows = shows + 1 WHERE bID = '$niz[$a]'");

return true;

}

function click($id){

$sql = my_query("SELECT url FROM banners WHERE bID = '$id'");
if(mysql_num_rows($sql)>0){

	$r = mysql_fetch_assoc($sql);
	$sqlu = my_query("UPDATE banners SET clicks = clicks + 1 WHERE bID = '$id'");
	header("Location:".$r['url']);
	exit();
}
}

The two functions do what their name says they do... First one shows the randomly selected banner and the second one counts the clicks...

To explain further more:
I took gfoot's advice on how to make a randomizer so what I do here is make an array with id's of the banners and repeat each one according to the multiplier, so the banner that has multiplier 3 will be presented three times in an array $niz...
Then with array_rand() I take out one item of an array and present that banner...
After that the database is updated so it holds a new value of the shows field which is being incremented by one...

The click.php page looks like this:

if(isset($_GET['id']) && is_numeric($_GET['id'])){
	click($_GET['id']);
}

So it only calls out for the function click() with the selected id as an parameter...

Click() function checks the database to see if there is a banner with that id and if there is one it updates a database with incrementing clicks field. After that the page is being redirected to the url specified when the banner was uploaded...

getfile.php looks like this:

if(isset($_GET['id']) && is_numeric($_GET['id'])){
	$sql = my_query("SELECT fileType,file FROM banners WHERE bID = '$_GET[id]'");
	if(mysql_num_rows($sql)>0){
		$r = mysql_fetch_assoc($sql);
		header("Content-type: $r[fileType]");
		echo $r['file'];

}
}

And what should be clear from this is that it selects the banner itself which is placed in a file field and it type and uses this to show the banner...

The system is far from perfect, but it works as intended...

It accepts only gif's since I haven't figured out how to make it work with the swf files...