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@ischenkodv
Created December 23, 2009 23:33
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function calculate_median($arr) {
$count = count($arr); //total numbers in array
$middleval = floor(($count-1)/2); // find the middle value, or the lowest middle value
if($count % 2) { // odd number, middle is the median
$median = $arr[$middleval];
} else { // even number, calculate avg of 2 medians
$low = $arr[$middleval];
$high = $arr[$middleval+1];
$median = (($low+$high)/2);
}
return $median;
}
function calculate_average($arr) {
$count = count($arr); //total numbers in array
foreach ($arr as $value) {
$total = $total + $value; // total value of array numbers
}
$average = ($total/$count); // get average value
return $average;
}
@joshi1983
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These solutions are nicely understandable but not optimally efficient since they involve fully sorting the array before getting the median out of it.

The optimal efficiency for getting a median is actually O(n) not O(n log n). Have you tried implementing Hoare's Selection algorithm in PHP?
Someone else mentioned it at: http://stackoverflow.com/questions/4201292/on-algorithm-to-find-the-median-of-a-collection-of-numbers

@grenoult
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As BramVanroy and other mentioned, array needs to be sorted. In my case I used sort($arr);.

@steffanhalv
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Rewritten from javascript https://stackoverflow.com/a/45309555/2298745

Median PHP:

function median($values) {
  $count = count($values);
  if ($count === 0)  return null;
  asort($values);
  $half = floor($count / 2);
  if ($count % 2) return $values[$half];
  return ($values[$half - 1] + $values[$half]) / 2.0;
}

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