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PHP array: Ranking items based on number of duplicates

Posted on 2008-06-20
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Last Modified: 2012-06-22
I want to find a more efficient way to build an associated array of strings that's arranged by how many duplicates are found within said array. For example if I have a list of words:
Apple, Peach, Peach, Lemon, Lemon, Orange, Orange, Orange

it will output like:
Orange (3)
Lemon (2)
Peach (2)
Apple (1)

Attached is the solution I came up with, but it's sloppy and really inefficient.
for ($i = 0; $i < count($fruits); ++ $i)

   {

      $count = 0;

      for ($y = 0; $y < count($fruits); ++ $y)

      {

         if($fruits[$i] == $fruits[$y])

         {

            $count++;

         }

      }

      $results[$fruits[$i]] = $count;

      asort($results, SORT_NUMERIC);

      $results = array_reverse($results);

   }
 

   foreach ($results as $key => $value)

   {

      if($value > 1)

         echo '(' . $value.') '.$key .'<br />';

   }

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Question by:troubledFish
  • 2
3 Comments
 
LVL 10

Expert Comment

by:wildzero
ID: 21835999
How about eithe of these two
$results = array();

$number_fruits = count($fruits);

for ($i = 0; $i < $number_fruits; ++ $i)

{

  $fruit = $fruits[$i];

  If (isset($results[$fruit])) {

    $count = $results[$fruit]++

  } else {

    $count = 1;  

  }      

  $results[$fruit] = $count;

}
 

asort($results, SORT_NUMERIC);

$results = array_reverse($results);

  

foreach ($results as $key => $value)

{

  if($value > 1)

    echo '(' . $value.') '.$key .'<br />';

}
 
 

or based on your first one. Just move the sort OUT of the loop.
 

for ($i = 0; $i < count($fruits); ++ $i)

   {

      $count = 0;

      for ($y = 0; $y < count($fruits); ++ $y)

      {

         if($fruits[$i] == $fruits[$y])

         {

            $count++;

         }

      }

      $results[$fruits[$i]] = $count;

   }

  asort($results, SORT_NUMERIC);

  $results = array_reverse($results);
 

   foreach ($results as $key => $value)

   {

      if($value > 1)

         echo '(' . $value.') '.$key .'<br />';

   }

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LVL 10

Expert Comment

by:wildzero
ID: 21836002
Actually, just use the first of my ones. That second one (and your original one) is just a bit crazy.
0
 
LVL 16

Accepted Solution

by:
DrNikon224 earned 500 total points
ID: 21836007
array_count_values() - http://www.php.net/array_count_values
arsort() - http://www.php.net/arsort

The function array_count_values() gives you an array with the count of each value stored within, and arsort() will sort the array by value in reverse.
<?

$arr = array("Apple","Peach","Peach","Lemon","Lemon","Orange","Orange","Orange");
 

$repeats = array_count_values($arr);
 

arsort($repeats);

?>

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