Filter array for duplicates and display it as string

Question

I need to display values from [dr-spec] array below and filter duplicates:

Array
(
    [0] => Array
        (
            [dr-spec] => Array
                (
                    [0] => Oncology
                )

        )

    [1] => Array
        (
            [dr-spec] => Array
                (
                    [0] => Plastic Surgery
                    [1] => Dental
                )
        )

    [2] => Array
        (
     
            [dr-spec] => Array
                (
                    [0] => Oncology
                    [1] => Plastic Surgery
                )
        )

)

After two days of trials and errors I made this:

<?php 
 foreach( $attributes['doctor'] as $doctor ): // Loop through the top array
   foreach( $doctor['dr-spec'] as $spec ): // Loop through the dr-spec array
    $result[] = $spec; // assign string into a new array
   endforeach;
 endforeach;
 $result = array_unique($result); // filter duplicates inside the array
 foreach( $result as $result ): 
  echo $result // html ommitted 
<?php endforeach; ?>

Maybe there's a better (compact) way of doing it?

Any help appreciated.

Do you need to keep the array as it is or is a flat array OK? — Andreas
– Andreas, Commented Aug 11, 2020 at 14:32

AbraCadaver · Accepted Answer · 2020-08-11 14:44:44Z

1

You can get all items in the dr-spec of all subarrays, merge them into a single array and then get the unique values:

$result = array_unique(array_merge(...array_column($attributes['doctor'], 'dr-spec')));

Just for learning purposes using your current code, you could check if it's in the array to eliminate the array_unique:

 foreach( $attributes['doctor'] as $doctor ): // Loop through the top array
   foreach( $doctor['dr-spec'] as $spec ): // Loop through the dr-spec array
    if(!in_array($spec, $result)) {
        $result[] = $spec; // assign string into a new array
    }
   endforeach;
 endforeach;

Or merge them to eliminate the second loop:

 $result = [];
 foreach( $attributes['doctor'] as $doctor ): // Loop through the top array
    $result = array_merge($result, $doctor['dr-spec']);
 endforeach;
 $result = array_unique($result);

edited Aug 11, 2020 at 14:44

answered Aug 11, 2020 at 14:38

AbraCadaver

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4 Comments

Andreas Over a year ago

The second version with in_array is probably inefficient. But then again how many specialities does one doctor have? Unless Dr. Nick or Dr. Phil is on the payroll

AbraCadaver Over a year ago

Yes, that's just for different ways of doing it; pandemic, working from home, bored...

Andreas Over a year ago

If you want another way of doing it then add array_flip(array_flip($arr)) that is said to be faster than array_unique

Rookie Over a year ago

@AbraCadaver, thanks for the solution. Didn't think about !in_array - good idea.

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