De-duplication of values of a multidimensional array

Question

I need to remove duplicate values from an array.

$original_array

Array
(
    [0] => 1 500 2 4 100 51 52
    [1] => 515 5 500
    [2] => 31 351 5 51 61 71 81 91
    [3] => 1 57 101
    [4] => 191 25 101 102
)

I thought I’d then be able to explode them by space to create a multidimensional array, and then use array_unique() but that’s not working.

# Create new array
$new_array = array();

# Loop through original_array
foreach($original_array as $original_array_value)
{
    $new_array[] = explode(' ', $original_array_value);
}
print_r($new_array);

Output:

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 500
            [2] => 2
            [3] => 4
            [4] => 100
            [5] => 51
            [6] => 52
        )

    [1] => Array
        (
            [0] => 515
            [1] => 5
            [2] => 500
        )

    [2] => Array
        (
            [0] => 31
            [1] => 351
            [2] => 5
            [3] => 51
            [4] => 61
            [5] => 71
            [6] => 81
            [7] => 91
        )

    [3] => Array
        (
            [0] => 1
            [1] => 57
            [2] => 101
        )

    [4] => Array
        (
            [0] => 191
            [1] => 25
            [2] => 101
            [3] => 102
        )

)

The final array result doesn't really matter to me as long as there are no duplicate values.

Answer 1

How about:

$arr = array(
    0 => '1 500 2 4 100 51 52',
    1 => '515 5 500',
    2 => '31 351 5 51 61 71 81 91',
    3 => '1 57 101',
    4 => '191 25 101 102',
);

$imp = trim(implode(' ',$arr));
$exp = array_unique(explode(' ', $imp));
var_dump($exp);

OUTPUT

Array
(
    [0] => 1
    [1] => 500
    [2] => 2
    [3] => 4
    [4] => 100
    [5] => 51
    [6] => 52
    [7] => 515
    [8] => 5
    [10] => 31
    [11] => 351
    [14] => 61
    [15] => 71
    [16] => 81
    [17] => 91
    [19] => 57
    [20] => 101
    [21] => 191
    [22] => 25
    [24] => 102
)

Answer 2

You're halfway there. Add this to the end of your code:

$final_array = array();
foreach($new_array as $index => $subarray) {
    $final_array = array_merge($final_array, $subarray);
}
$final_array = array_unique($final_array);

Then the code looks like this:

$original_array = array(
    '1 500 2 4 100 51 52',
    '515 5 500',
    '31 351 5 51 61 71 81 91',
    '1 57 101',
    '191 25 101 102'
    );

# Create new array.
$new_array=array();

# Loop through original_array.
foreach($original_array as $original_array_value)
{
    $new_array[]=explode(' ', $original_array_value);
}
$final_array = array();
foreach($new_array as $index => $subarray) {
    $final_array = array_merge($final_array, $subarray);
}
$final_array = array_unique($final_array);

echo "<pre>";
print_r($final_array);
echo "</pre>";

Even better: combine steps, like so:

$original_array = array(
    '1 500 2 4 100 51 52',
    '515 5 500',
    '31 351 5 51 61 71 81 91',
    '1 57 101',
    '191 25 101 102'
    );

# Create new array.
$final_array =array();

# Loop through original_array and do the merge at the same time.
foreach($original_array as $original_array_value)
{
    $final_array = array_merge($final_array, explode(' ', $original_array_value) );
}
$final_array = array_unique($final_array);

echo "<pre>";
print_r($final_array);
echo "</pre>";

Answer 3

Instead of using array_unique() you can build a unique array straight away:

$arr = array(
    0 => '1 500 2 4 100 51 52',
    1 => '515 5 500',
    2 => '31 351 5 51 61 71 81 91',
    3 => '1 57 101',
    4 => '191 25 101 102',
);

$result = array();

foreach ($arr as $item) {
        $result += array_flip(explode(' ', $item));
}

The + operator adds new values to the array if their corresponding keys don't already exist. In the end, you can find the answer by observing the array keys:

print_r(array_keys($result));