Remove duplicates from array and increment a value

Question

I'm trying to write a script that will make produce an easy overview over a list of orders.

I have an array that looks like this:

Array(

    [0]=>Array(
              [0] => name of product 1
              [1] => name of options for product
              [3] => quantity (an integer)
              )
    [1]=>Array(
              [0] => name of product 2
              [1] => name of options for product
              [3] => quantity (an integer)
              )
    etc.
)

What I want to do is to check where keys [0] and [1], i.e the same product with the same options, and remove duplicates. At the same time, I want the value [3] to be incremented with the number in the arrays that were removed. To simplify, I want to merge value [3] where product and options match. I've been thinking about this for a long time but can't figure out how to do it. Any suggestions?

Felix Kling · Accepted Answer · 2010-11-25 00:00:56Z

3

You can loop over the array and use an associative array to "count" the products:

$merged = array();

foreach($products as $product) {
    $key = $product[0] . $product[1];
    if(!array_key_exists($key, $merged)) {
        $merged[$key] = $product;
    }
    else {
        $merged[$key][3] += $product[3];
    }
}

The trick here is that the name and the options of a product are concatenated to form a unique product key. Of course that requires that the options for a product are always in the same order.

Working Demo

edited Nov 25, 2010 at 0:00

answered Nov 24, 2010 at 23:54

Felix Kling

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1 Comment

Toxid Over a year ago

Wow! This is a terrific script for my purpose. I was experimenting with in_array() before but I didn't get very far. Thanks alot!

Rahly · Accepted Answer · 2010-11-24 23:57:37Z

0

Dual loops

<?php
for($counter=0;$counter<count($arr)-1;$counter++){
  $counter2 = $counter+1;
  while($counter2<count($arr)) {
    if( $arr[$counter][0] == $arr[$counter2][0] &&
        $arr[$counter][1] == $arr[$counter2][1] ) {
       // Same product
       $arr[$counter][2]+=$arr[$counter2][2];
       array_splice($arr, $counter2, 1);
    } else {
      $counter2++;
    }
  }
}
?>

answered Nov 24, 2010 at 23:57

Rahly

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2 Comments

dkamins Over a year ago

Note that this is O(n^2) which will be horribly slow on large lists.

Rahly Over a year ago

True, but, if $arr only has one reference, the array_splice will not allocate new memory for an array. Making a copy of an array which you may or may not remove elements will at most double the memory usage. With a large list you have higher chance of running out of available php memory.

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