Question

I’m trying hard to wrap my head around what I’m doing here, but having some difficulty… Any help or direction would be greatly appreciated.

So I have some values in a table I’ve extracted according to an array (brilliantly named $array) I’ve predefined. This is how I did it:

foreach ($array as $value) {

$query = "SELECT * FROM b_table WHERE levelname='$value'";
$result = runquery($query);
$num = mysql_numrows($result);

$i=0;
while ($i < 1) {
$evochance=@mysql_result($result,$i,"evochance");  // These values are integers that will add up to 100. So in one example, $evochance would be 60, 15 and 25 if there were 3 values for the 3 $value that were returned.
$i++;
}

Now I can’t figure out where to go from here. $evochance represent percentage chances that are linked to each $value.
Say the the favourable 60% one is selected via some function, it will then insert the $value it’s linked with into a different table.

I know it won’t help, but the most I came up with was:

if (mt_rand(1,100)<$evochance) {
$valid = "True";
} 
else {
$valid = "False";
}
echo "$value chance: $evochance ($valid)<br />\n"; // Added just to see the output.

Well this is obviously not what I’m looking for. And I can’t really have a dynamic amount of percentages with this method. Plus, this sometimes outputs a False on both and other times a True on both.

So, I’m an amateur learning the ropes and I’ve had a go at it. Any direction is welcome.
Thanks =)

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**Edit 3 (cleaned up):

@cdburgess I’m sorry for my weak explanations; I’m in the process of trying to grasp this too. Hope you can make sense of it.

Example of what’s in my array: $array = array('one', 'two', 'three')

Well let’s say there are 3 values in $array like above (Though it won’t always be 3 every time this script is run). I’m grabbing all records from a table that contain those values in a specific field (called ‘levelname’). Since those values are unique to each record, it will only ever pull as many records as there are values. Now each record in that table has a field called evochance. Within that field is a single number between 1 and 100. The 3 records that I queried earlier (Within a foreach ()) will have evochance numbers that sum up to 100. The function I need decides which record I will use based on the ‘evochance’ number it contains. If it’s 99, then I want that to be used 99% of the time this script is run.

HOWEVER… I don’t want a simple weighted chance function for a single number. I want it to select which percentage = true out of n percentages (when n = the number of values in the array). This way, the percentage that returns as true will relate to the levelname so that I can select it (Or at least that’s what I’m trying to do).

Also, for clarification: The record that’s selected will contain unique information in one of its fields (This is one of the unique values from $array that I queried the table with earlier). I then want to UPDATE another table (a_table) with that value.

So you see, the only thing I can’t wrap my head around is the percentage chance selection function… It’s quite complicated to me, and I might be going about it in a really round-about way, so if there’s an alternative way, I’d surely give it a try.
To the answer I’ve received: I’m giving that a go now and seeing what I can do. Thanks for your input =)**

Answer 1

I think I understand what you are asking. If I understand correctly, the “percentage chance” is how often the record should be selected. In order to determine that, you must actually track when a record is selected by incrementing a value each time the record is used. There is nothing “random” about what you are doing, so a mt_rand() or rand() function is not in order.

Here is what I suggest, if I understood correctly. I will simplify the code for readability:

<?php

$value = 'one';   // this can be turned into an array and looped through
$query1 = "SELECT sum(times_chosen) FROM `b_table` WHERE `levelname` = '$value'";
$count =  /* result from $query1 */
$count = $count + 1; // increment the value for this selection

// get the list of items by order of percentage chance highest to lowest
$query2 = "SELECT id, percentage_chance, times_chosen, name FROM `b_table` WHERE `levelname` = '$value' ORDER BY percentage_chance DESC";
$records = /* results from query 2 */
// percentage_chance INT (.01 to 1) 10% to 100%
foreach($records as $row) {
    if(ceil($row['percentage_chance'] * $count) > $row['times_chosen']) {
        // chose this record to use and increment times_chosen
        $selected_record = $row['name'];
        $update_query = "UPDATE `b_table` SET times_chosen = times_chosen + 1 WHERE id = $row['id']";
        /* run query against DB */
        // exit foreach (stop processing records because the selection is made)
        break 1;
    }
}

// check here to make sure a record was selected, if not, then take record 1 and use it but
// don't forget to increment times_chosen

?>

This should explain itself, but in a nutshell, you are telling the routine to order the database records by the percentage chance highest chance first. Then, if percentage chance is greater than total, skip it and go to the next record.

UPDATE: So, given this set of records:

$records = array(
    1 => array(
        'id' => 1001, 'percentage_chance' => .67, 'name' => 'Function A', 'times_chosen' => 0,
    ),
    2 => array(
        'id' => 1002, 'percentage_chance' => .21, 'name' => 'Function A', 'times_chosen' => 0,
    ),
    3 => array(
        'id' => 1003, 'percentage_chance' => .12, 'name' => 'Function A', 'times_chosen' => 0,
    )
);

Record 1 will be chosen 67% of the time, record 2 21% of the time, and record 3 12% of the time.