How to find & replace duplicate value(s) in a multidimentional array

Question

I have a script that allows a user to submit a form. Each form submission creates a new line (array) which is displayed in a textarea named $pvrbs['pramtrs']. Each value of each array is separated by a double-pipe in the textarea. When the user finishes adding lines to the textarea, he clicks on a button which saves the textarea to a flat file.

Below is a snippet of the function that creates the multidimensional array and the flat file:

function create_pcFile($pName) {    
    $pcnf = "<" . "?php  \n";
    $pur = explode("\n",stripslashes(trim($pvrbs['pramtrs'])));
    $pcnt = 0;
    $uses = 0;
    $cnAry = array();
    foreach ($pur as $pline) {
        $pline = trim($pline);
        $lary = explode("||",$pline);
        
        if ( !verify_cd($lary[0]) ) { $lary[0] = "<<<ERROR>>>"; }
        if ( !verify_url($lary[1]) ) { $lary[1] = "<<<ERROR>>>"; }
        if ( !verify_securerpage($lary[2]) ) { $lary[2] = "<<<ERROR>>>"; }
        if ( !verify_url($lary[3]) ) { $lary[3] = "<<<ERROR>>>"; }
        if ( !verify_date($lary[4]) ) { $lary[4] = "<<<ERROR>>>"; }
        if ( !verify_date($lary[5]) ) { $lary[5] = "<<<ERROR>>>"; }
        if ( !verify_uss($lary[6]) ) { $lary[6] = "<<<ERROR>>>"; }
        
        if( (isset($lary[0])) && (isset($lary[1])) && (isset($lary[2])) && (isset($lary[3])) && (isset($lary[4])) && (isset($lary[5])) && (isset($lary[6]))) {
            $cnAry[] = $lary;
        }
    }
    $Stg = '';              
    if(is_array($cnAry) && !empty($cnAry) ) {               
        foreach ($cnAry as $ary) {                   
                $Stg .= "array(\"" . $ary[0] . "\", \"" . $ary[1] . "\", \"" . $ary[2] . "\", \"" . $ary[3] . "\", \"" . $ary[4] . "\", \"" . $ary[5] . "\", \"" . $ary[6] . "\"), ";
        }
    }
    $pcnf .= "$" . "params = array(" . rtrim($parStg, ", ") . ");\n";   // Trim ", " off of final array.
    $pcnf .= "$" . "erPage = \"" . $pvrbs['erPage'] . "\";\n";
    $pcnf .= "?" . ">";         
    $x = start_file($pName, $pcnf);
    return;
}

Below is an example of the textarea with a duplicate 111:

111||https://1.com/||No||https://e.com/||07/12/2020||07/30/2021||2
222||https://2.com||No||https://3.com||07/30/2020||07/30/2021||5
111||https://6.com||No||https://4.net||07/30/2020||07/30/2021||7

Below is the flat file that corresponds to the textarea above:

<?php  
$params = array(array("111", "https://1.com/", "No", "https://e.com/", "07/12/2020", "07/30/2021", "2"), array("222", "https://2.com", "No", "https://3.com", "07/30/2020", "07/30/2021", "5"), array("111", "https://6.com", "No", "https://4.net", "07/30/2020", "07/30/2021", "7"));
$erPage = "https://t.com";
?>

What code do I need to add to the function that will find and replace duplicates? I need the first value of each array $lary[0] to be unique. Using the examples above, the second instance of 111 should be replaced with <<<DUPLICATE>>>.

Below is what the textarea should look like once the duplicate has been replaced:

111||https://1.com/||No||https://e.com/||07/12/2020||07/30/2021||2
222||https://2.com||No||https://3.com||07/30/2020||07/30/2021||5
<<<DUPLICATE>>>||https://6.com||No||https://4.net||07/30/2020||07/30/2021||7

Below is what the flat file should look like:

<?php  
$params = array(array("111", "https://1.com/", "No", "https://e.com/", "07/12/2020", "07/30/2021", "2"), array("222", "https://2.com", "No", "https://3.com", "07/30/2020", "07/30/2021", "5"), array("<<<DUPLICATE>>>", "https://6.com", "No", "https://4.net", "07/30/2020", "07/30/2021", "7"));
$erPage = "https://t.com";
?>

kmoser · Accepted Answer · 2020-07-31 03:18:48Z

1

Rather than saying:

$cnAry[] = $lary;

Do this:

if ( array_key_exists( $lary[0], $keys ) ) {
  // Duplicate!
  $lary[0] = '<<<DUPLICATE>>>';
} else {
  // Original (not dupe)
  $keys[ $lary[0] ] = true;
}
$cnAry[] = $lary;

Here's how it works:

$keys is an array of keys you've seen before. If $lary[0] exists in $keys then it's a dupe and we change $lary[0] to <<<DUPLICATE>>> before appending it to $cnAry.

If $lary[0] doesn't exist in $keys, that means it's original (not a dupe) so we add that key to $keys to track that we've just seen it.

Also, you should probably declare the $keys = []; variable before your loop, to avoid PHP warnings.

answered Jul 31, 2020 at 3:18

kmoser

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1 Comment

Jeff Over a year ago

Thank you! Works great. So glad you mentioned declaring $keys = [];. Saved me from another headache.

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