How to remove duplicate data in an array? - php

Question

I have the following array:
Array
(
[0] => Array
(
[Import] => Array
(
[product_id] => 1
[id] => 1
[category_id] => 1
[amount] => 50
[cost] => 8320
[paid] => 0
[comment] => transportation and others cost: 100
[created] => 2015-06-22 12:09:20
)
[0] => Array
(
[total_sell] => 6
)
)
[1] => Array
(
[Import] => Array
(
[product_id] => 2
[id] => 2
[category_id] => 2
[amount] => 15
[cost] => 3000
[paid] => 0
[comment] =>
[created] => 2015-06-22 12:10:36
)
[0] => Array
(
[total_sell] => 1
)
)
[2] => Array
(
[Import] => Array
(
[product_id] => 1
[id] => 3
[category_id] => 1
[amount] => 15
[cost] => 2000
[paid] => 0
[comment] =>
[created] => 2015-06-22 12:10:58
)
[0] => Array
(
[total_sell] => 6
)
)
[3] => Array
(
[Import] => Array
(
[product_id] => 1
[id] => 4
[category_id] => 1
[amount] => 50
[cost] => 8000
[paid] => 0
[comment] =>
[created] => 2015-06-23 01:10:10
)
[0] => Array
(
[total_sell] => 6
)
)
)
I want to remove duplicate entry of [Import][product_id]. So my expected result is :
Array
(
[0] => Array
(
[Import] => Array
(
[product_id] => 1
[id] => 1
[category_id] => 1
[amount] => 50
[cost] => 8320
[paid] => 0
[comment] => transportation and others cost: 100
[created] => 2015-06-22 12:09:20
)
[0] => Array
(
[total_sell] => 6
)
)
[1] => Array
(
[Import] => Array
(
[product_id] => 2
[id] => 2
[category_id] => 2
[amount] => 15
[cost] => 3000
[paid] => 0
[comment] =>
[created] => 2015-06-22 12:10:36
)
[0] => Array
(
[total_sell] => 1
)
)
)
Would you write a function to filter this type of array and produce expected result. I have been googling for 2 days but no luck.

Answer 1

This is a handy one liner that should do the trick:
$unique= array_map("unserialize", array_unique(array_map("serialize", $original)));
If the underlying arrays are not identical, that won't work, in which case I think you could do:
$unique = array_intersect_key($original ,
array_unique(
array_map(function($item) {
return $item['Import']['product_id'];
}, $original)
)
);
Tested: http://sandbox.onlinephpfunctions.com/code/8aee5cbd614e0ddd1a03dfaa7e98c72fbbe7d68d

Answer 2

Here is a quick stable sort and reduce which runs in linearithmic time. First-encountered product Id's are kept, and entries with duplicate product Id's are ignored.
// Stable sort
sort($in);
// Reduce
$out = array_reduce($in, function(&$acc, &$item){
if($item['Import']['product_id'] !== #$acc[sizeof($acc)-1]['Import']['product_id']) {
$acc[] = $item;
}
return $acc;
}, []);
Demo: http://ideone.com/BP0eUJ
Update: Here is an even better linear-time algorithm that does the same as above using a fast "hash table" lookup. Again, the first-encountered product Id is kept and subsequent ones of the same Id are ignored.
$out = [];
$hashTable = [];
foreach($in as $item) {
$pid = $item['Import']['product_id'];
if(!isset($hashTable[$pid])) {
$out[] = $item;
$hashTable[$pid] = true;
}
}
Demo: http://ideone.com/5RF0og