1

I have an array that looks like this:

PHP Syntax (Toggle Plain Text)
    array
      0 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '00:00' (length=5)
          2 => string '34.83' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '00:00' (length=5)
          5 => string '34.83' (length=5)
      1 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '01:00' (length=5)
          2 => string '32.07' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '01:00' (length=5)
          5 => string '32.07' (length=5)
      2 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '02:00' (length=5)
          2 => string '28.69' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '02:00' (length=5)
          5 => string '28.69' (length=5)
      3 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '03:00' (length=5)
          2 => string '28.17' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '03:00' (length=5)
          5 => string '28.17' (length=5)

What I'm trying to do is average each 2/5 element with eachother into > a new array with the Date/Time. so have something like

array
0 => 
array
0 => string '12/08/2011' (length=10)
1 => string '00:00' (length=5)
2 => string 'AVERAGE OF 2&5' (length=5)
PHP Syntax (Toggle Plain Text)
      1 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '01:00' (length=5)
          2 => string 'AVERAGE OF 2&5' (length=5)
      2 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '02:00' (length=5)
          2 => string 'AVERAGE OF 2&5' (length=5)
      3 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '03:00' (length=5)
          2 => string 'AVERAGE OF 2&5' (length=5)

Any help would be appreciated, i've been trying ot figure this out for a couple of hours now and can't wrap my head around achieving this? ... Do i need to explode the elements to their own array, average then reinsert?

thank you.

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2
  • Explode what? Those look to be numbers already, so there should be no need to do any further exploding. Commented Dec 7, 2011 at 18:45
  • Sorry i had the Titel wrong-I'm looking to Average each 2/5 value of the original array and insert that value to the corresponding key... Commented Dec 7, 2011 at 18:56

2 Answers 2

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2

If you have php5.3+ you can do this in two lines (and one if you like difficult to read function calls) using a closure with array_map:

$f = function($x) { return array($x[0], $x[1], ($x[2]+$x[5])/2); };
$new = array_map($f, $arr);
print_r($new);

The closure returns a new array with the two values you requested and averages the values of keys 2 and 5.

If you don't have PHP5.3, use a regular function:

function dan_is_awesome($x) { return array($x[0], $x[1], ($x[2]+$x[5])/2); };
$new = array_map('dan_is_awesome', $arr);
print_r($new);

array_map() takes as its first argument a callback function that it then performs on each element of the input array.

UPDATE

Stack Overflow IS NOT a substitute for logical thinking. "Can you do this for me" is not a legitimate question. However ...

If you needed to accomodate the requirements listed in the comment below (averaging keys 2/5/7/10/12/15 ... and so on to the end of the array) you could do:

function dan_is_awesome($x)
{
  $avg_vals = array($x[2], $x[5]);

  $i = 10;
  while ($i < count($x)) {
    if ($i % 10 == 0     // divisible by 10
      || $i-5 % 10 == 0  // divisible by 5
      || $i % 2 == 0     // divisible by 2
    ) { 
      $avg_vals[] = $x[$i];
    }
    ++$i;
  }

  $avg = array_sum($avg_vals) / count($avg_vals);

  return array($x[0], $x[1], $avg);
};

$new = array_map('dan_is_awesome', $arr);
print_r($new);
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7 Comments

Ya'll both just saved me loads of time, I coudln't comprehend it for some reason. Anyway thank you.
what if the array is is 132 values, and i need value 2,5 and then every 5th after that .. so 7/10 12/15 17/20 and so on up to 132
@tgr0ss Updated code with example of averaging values as you requested
Nice function name. I'd agree at this moment.
Yeah you see that function name in a lot of serious programming textbooks, so i figured, "When in Rome" ... :)
|
0

I prefer rdlowrey's methods, but this is likely easier to understand for most people.

foreach ($arr as $key => $subArray) {
    $ave = ($subArray[2] + $subArray[5]) / 2;
    $arr[$key] = array($subArray[0], $subArray[1], $ave);
}
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3 Comments

what if the array is is 132 values, and i need value 2,5 and then every 5th after that .. so 7/10 12/15 17/20 and so on up to 132
What did you try? Read the code, and try to understand it. THe modification needed should be quite clear to you.
I tried to do a for loop around it with $i=2;$i<132;i+=5 and one for n=5 " " .. Which then gave me undefined offset in five before i even did anything. .. otherwise I'd do one giant query with a + $subArray[2] +""[5] +""[7]+""[10] and so on?

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