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PHP Array Exercises : Find unique values from multidimensional array and flatten them in zero depth

PHP Array: Exercise-42 with Solution

Write a PHP function to find unique values from multidimensional arrays and flatten them in 0 depth.

Sample Solution:

PHP Code:

<?php
function array_flat($my_array) 
    { 
         $fa = array();
		 $l = 0;
        foreach($my_array as $k => $v ) 
        { 
            if( !is_array( $v ) ) 
            { 
               $fa[ ]= $v; 
                
                continue;           
            } 
             $l++; 
            $fa= array_flat( $v, $fa, $l ); 
            $l--; 
      } 
       
        if( $l == 0 ) $fa = array_values( array_unique( $fa ) );         
        return $fa;       
    } 
$tmp = array( 'a' => array( -1,-2, 0, 2, 3 ), 'b' => array( 'c' => array( -1, 0, 2, 0, 3 ) ) ); 
print_r(array_flat($tmp));
?>

Sample Output: 

Array                                                       
(                                                           
    [0] => -1                                               
    [1] => 0                                                
    [2] => 2                                                
    [3] => 3                                                
)

Flowchart:

Flowchart: PHP - Find unique values from multidimensional array and flatten them in zero depth

PHP Code Editor:

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Previous: Write a PHP program to identify the email addresses which are not unique.
Next: Write a PHP script to merge two commas separated lists with unique value only.

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC