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1 <?php |
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2 // $Id: ad_weight_probability.inc,v 1.1.4.3 2009/02/28 05:48:42 jeremy Exp $ |
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3 |
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4 /** |
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5 * @file |
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6 * A plug in for the ad.module, allowing an admin to set the probability that |
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7 * a given advertisement will be displayed. |
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8 * |
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9 * Copyright (c) 2008-2009. |
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10 * Jeremy Andrews <jeremy@tag1consulting.com>. |
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11 */ |
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12 |
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13 function ad_weight_probability_cache_filter($ads) { |
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14 $display = array(); |
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15 if (is_array($ads)) { |
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16 $probability = array(); |
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17 $cache = adserve_cache('get_cache', 'weight'); |
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18 foreach ($ads as $aid) { |
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19 $probability[] = isset($cache['probability'][$aid]) ? $cache['probability'][$aid] : 0; |
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20 } |
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21 $gcd = ad_weight_probability_gcd($probability); |
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22 _debug_echo("ad_weight_probability cache_filter gcd($gcd)"); |
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23 foreach ($ads as $aid) { |
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24 $weight = (isset($cache['probability'][$aid]) && $gcd) ? $cache['probability'][$aid] / $gcd : 0; |
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25 _debug_echo("ad_weight_probability cache_filter aid($aid) weight($weight)"); |
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26 for ($i = 1; $i <= $weight; $i++) { |
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27 $display[] = $aid; |
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28 } |
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29 } |
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30 } |
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31 return $display; |
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32 } |
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33 |
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34 /** |
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35 * Returns the greatest common divisor of an array of integers. |
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36 */ |
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37 function ad_weight_probability_gcd($integers) { |
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38 $gcd = array_shift($integers); |
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39 |
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40 while (!empty($integers)) { |
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41 $gcd = _ad_weight_probability_gcd($gcd, array_shift($integers)); |
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42 } |
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43 return $gcd; |
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44 } |
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45 |
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46 /** |
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47 * Helper function to calculate the greatest common divisor using the Euclidean |
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48 * algorithm (http://en.wikipedia.org/wiki/Euclidean_algorithm). |
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49 */ |
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50 function _ad_weight_probability_gcd($a, $b) { |
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51 if ($b == 0) { |
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52 return $a; |
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53 } |
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54 else { |
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55 return _ad_weight_probability_gcd($b, $a % $b); |
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56 } |
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57 } |
