Merge array rows based on two columns and sum another column

Question

I have this array:

array(
    array('id' => 1, 'price' => 20.00, 'stock' => 2, 'year' => 11 ),
    array('id' => 1, 'price' => 20.00, 'stock' => 3, 'year' => 12 ),
    array('id' => 1, 'price' => 20.00, 'stock' => 2, 'year' => 13 ),
    array('id' => 2, 'price' => 36.00, 'stock' => 11, 'year' => 13 ),
);

I need to sum the "stock" column when the id is the same (is the same article) and the years are 12 AND 13.

The result should be:

array(
    array('id' => 1, 'price' => 20.00, 'stock' => 2, 'year' => 11 ),
    array('id' => 1, 'price' => 20.00, 'stock' => 5, 'year' => 13 ),
    array('id' => 2, 'price' => 36.00, 'stock' => 11, 'year' => 13 ),
);

Notice the 'year' => 12 has been removed and the stock of that row has been added to the 13 row.

I can't do this without creating a big mess of spaguetti code with a bunch of bucles. Maybe there is a php function to this in a cleaner way?

Sorry for my english.

A PHP function that groups certain rows of a multidimensional array (specified by some arbitrary condition), sums a specific column and assumes that the non-grouped, non-summed columns have the same value (because otherwise the grouping would not make sense)? No. But SQL does that. Perhaps you should look there for the solution? — Jon
– Jon, Commented Nov 18, 2013 at 13:07
It's a good idea, but how can i group by year when its 12 or 13? not always — Carlos Goce
– Carlos Goce, Commented Nov 18, 2013 at 13:26

Ronald Hulshof · Accepted Answer · 2013-11-18 14:51:57Z

3

If you insist on solving this issue using PHP instead of your database, this will do the trick:

function group_sum($array) 
{
    $return = array();

    foreach ($array as $v)
    {
        $key = $v['id'] . '_' . ($v['year'] == 12 ? 13 : $v['year']);

        if (array_key_exists($key, $return))
        {
            $return[$key]['stock'] += $v['stock'];

            if ($v['year'] > $return[$key]['year'])
                $return[$key]['year'] = $v['year'];
        }
        else
        {
            $return[$key] = $v;
        }
    }

    return $return;
}

edited Nov 18, 2013 at 14:51

answered Nov 18, 2013 at 14:23

Ronald Hulshof

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Comments

Mark · Accepted Answer · 2013-11-18 13:53:55Z

0

I try and reach upto here...Please anyone can push this code little...

$ary = array(
  array('id' => 1, 'price' => 20.00, 'stock' => 8, 'year' => 11 ),
  array('id' => 1, 'price' => 20.00, 'stock' => 3, 'year' => 12 ),
  array('id' => 1, 'price' => 20.00, 'stock' => 2, 'year' => 13 ),
  array('id' => 2, 'price' => 36.00, 'stock' => 11, 'year' => 13 ),
);

$ary2 = $ary;
$i=0;
foreach($ary as $row){

foreach($ary2 as $row2){
    if($row['id']==$row2['id'] && $row['year'] > $row2['year']){
        $ary[$i]['stock'] = $row['stock'] + $row2['stock'];
        unset($row);
    }   
}
//
$i++;
}
echo "<pre/>";
print_r($ary);

answered Nov 18, 2013 at 13:53

Mark

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