Preventing Duplicates in Array

Question

I have an array I'm pulling from a MySQL db and I need to reformat it into another array without any duplicates on a specific key.

Original array:

Array // $categories array
(
    [0] => Array
        (
            [name] => Body & Bath Products
            [keyword] => body-and-bath-products
        )
    [more ...]
)

New array structure:

Array // $links array
(
    [0] => Array
        (
            [keyword] => Body & Bath Products
            [link] => ./Body-and-Bath-Products
            [target] => _self
            [tooltip] => 1
        )
    [more ...]
)

Looping through with PHP:

$links = array();

foreach ($categories as $cat):
    if (in_array ($cat['name'], $links)):
        continue;
    else:
        $links[] = array(
            'keyword' => $cat['name'],
            'link' => './' . $this->url->cap_keyword($cat['keyword']),
            'target' => '_self',
            'tooltip' => true
        );
    endif;
endforeach;

But this isn't working, still getting all 534 entries in my $links array.

I know it's something simple but I'm just missing it somehow ...

Well mate the problem you have is $cat['name'] will never be a key in $links array. If you var_dump() your $links array you will see that the keys are actually indexes from 0 to n. — Sterling Duchess
– Sterling Duchess, Commented Sep 9, 2013 at 23:48
I understand that, how do I test the value of $links['keyword'] ? — secondman
– secondman, Commented Sep 9, 2013 at 23:49
can you talk about the recrods returned from the query and how you would like them structured (i.e. when you say "remove" duplicates what does this mean - group common values somehow, perform some sort of aggregation on duplicate values, etc.). You can probably achieve what you want in the query itself. — Mike Brant
– Mike Brant, Commented Sep 10, 2013 at 0:12

Steven · Accepted Answer · 2013-09-10 00:04:29Z

1

You could simply use another foreach loop...

$links = array();

foreach ($categories as $cat){

    foreach($links as $value){ // Loop through $links array
        if($value['keyword'] == $cat['name']) // Check if $cat['name'] is already in $links
            continue 2; // Skip rest of this loop and parent loop if it exists
    }


    $links[] = array(
        'keyword' => $cat['name'],
        'link' => './' . $this->url->cap_keyword($cat['keyword']),
        'target' => '_self',
        'tooltip' => true
        );
}

answered Sep 10, 2013 at 0:04

Steven

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Sterling Duchess · Accepted Answer · 2013-09-10 00:08:31Z

0

The problem you have mate is you are populating the $links array with indexed keys and when you are checking if key exists in the said array you are using $cat['name'] variable as key. Since that is never actually in the $links array you get duplicates.

$links = array();

foreach ($categories as $cat):
    if (in_array ($cat['name'], $links)): // HERE YOU CHECK IF $links CONTAINS $cat['name'] HOWEVER YOU NEVER STORE $cat['name'] AS KEY
        continue;
    else:
        $links[] = array( // HERE YOU STORE EACH ENTRY WITH KEY AS INDEX FROM 0 TO N
            'keyword' => $cat['name'],
            'link' => './' . $this->url->cap_keyword($cat['keyword']),
            'target' => '_self',
            'tooltip' => true
        );
    endif;
endforeach;

The solution would be to store keys with $cat['name'] instead of index number.
$links = array();

foreach ($categories as $cat):
    if (array_key_exists ($cat['name'], $links)): 
        continue;
    else:
        $links[$cat['name']] = array( // You should save the entry using $cat['name'] as key for the entry this way when you do the in_array check you can prevent duplicates
            'keyword' => $cat['name'],
            'link' => './' . $this->url->cap_keyword($cat['keyword']),
            'target' => '_self',
            'tooltip' => true
        );
    endif;
endforeach;

You will need to substitute numerical keys with the key $cat['name'] and in_array() method with array_key_exists() method.

The problem with in_array() is it checks value of top array $links and $links never contains $cat['name'] as value because it's and array of arrays. The arrays in $links however do contain $cat['name'].

edited Sep 10, 2013 at 0:08

answered Sep 9, 2013 at 23:52

Sterling Duchess

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6 Comments

secondman Over a year ago

No that won't work, the keys need to be numeric. I need a different way to test other than in_array()

Sterling Duchess Over a year ago

You need to use array_key_exists()

secondman Over a year ago

array_key_exists() searches for keys while in_array() searches for values in the given array. Obviously as you mentioned, $cat['name'] will never appear as a key so it won't be found with array_key_exists()

Sterling Duchess Over a year ago

You did not check my solution at all. You tried using in_array to find $cat['name'] in $links which did not work as you had an array of arrays. Only way you could have kept your own code was to add $cat['name'] as keys and used array_key_exists() instead of in_array(). However you seem to have choose the unsafe way to do it.

Steven Over a year ago

How on earth is it unsafe?

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