PHP Unique Array by Value

PHP unique array by value?

basically

$unique_array = [];
foreach($your_array as $element) {
    $hash = $element[field-that-should-be-unique];
    $unique_array[$hash] = $element;
}
$result = array_values($unique_array);

How to remove duplicate values from an array in PHP

Use array_unique().

Example:

$array = array(1, 2, 2, 3);
$array = array_unique($array); // Array is now (1, 2, 3)

How to find unique values in array

You can use array_unique() in single line like below:-

<?php

$unique_array = array_unique($array); // get unique value from initial array

echo "<pre/>";print_r($unique_array); // print unique values array
?>

Output:- https://eval.in/601260

Reference:- http://php.net/manual/en/function.array-unique.php

If you want in string format:-

echo implode(',',$final_array);

Output:-https://eval.in/601261

The way you want is here:-

https://eval.in/601263

OR

https://eval.in/601279

unique array on base on value of specific key

You could simply loop through the array and add them to a new array, indexed by hotelID. This way any duplicates will just overwrite the existing value and you end up with one entry per hotel:

$unique = array();

foreach ($hotels as $value)
{
    $unique[$value['hotelID']] = $value;
}

$data['uniqueHotels'] = array_values($unique);

array_unique for objects?

Well, array_unique() compares the string value of the elements:

Note: Two elements are considered equal if and only if (string) $elem1 === (string) $elem2 i.e. when the string representation is the same, the first element will be used.

So make sure to implement the __toString() method in your class and that it outputs the same value for equal roles, e.g.

class Role {
    private $name;

    //.....

    public function __toString() {
        return $this->name;
    }

}

This would consider two roles as equal if they have the same name.

Need to get unique values in array

You can always do something like this:

$colorarray = array();
foreach($catIds as $catid){
    if(!in_array($catid, $colorarray) {
       $colorarray[] = $catid;
    }
}

But also this has n*n complexity, So if your array is way too big, it might not be the most optimised solution for you.

How to remove duplicate values from a multi-dimensional array in PHP

Here is another way. No intermediate variables are saved.

We used this to de-duplicate results from a variety of overlapping queries.

$input = array_map("unserialize", array_unique(array_map("serialize", $input)));

How can you get unique values from multiple arrays using array_unique?

The answer to the first part of your question is NO.

The array_unique function definition in the PHP manual states that array_unique takes exactly two arguments, one array, and an optional integer that determines the sorting behavior of the function.

array array_unique ( array $array [, int $sort_flags = SORT_STRING ] )

Rather than take the manual's word for it, here are some test arrays.

$one_array      = ['thing', 'another_thing', 'same_thing', 'same_thing'];
$two_arrays     = ['A', 'B', 'C', 'thing', 'same_thing'];
$or_more_arrays = ['same_thing', 1, 2, 3];

A couple of test show that the function does work as advertised:

$try_it = array_unique($one_array);

returns ['thing', 'another_thing', 'same_thing'];

$try_it = array_unique($one_array, $two_arrays);

gives you a warning

Warning: array_unique() expects parameter 2 to be integer, array given

and returns null.

$try_it = array_unique($one_array, $two_arrays, $or_more_arrays);

also gives you a warning

Warning: array_unique() expects at most 2 parameters, 3 given

and returns null.

---

The answer to the second part of your question is YES.

To get unique values using array_unique, you do have to have one array of values. You can do this, as u_mulder commented, by using array_merge to combine the various input arrays into one before using array_unique.

$unique = array_unique(array_merge($one_array, $two_arrays, $or_more_arrays));

returns

['thing', 'another_thing', 'same_thing', 'A', 'B', 'C', 1, 2, 3];

If instead of several individual array variables, you have an array of arrays like this:

$multi_array_example = [
    [1, 2, 3],
    [2, 3, 4], 
    [3, 4, 5],
    [4, 5, 6]
];

Then you can unpack the outer array into array merge to flatten it before using array_unique.

$unique = array_unique(array_merge(...$multi_array_example));

Or in older PHP versions (<5.6) before argument unpacking, you can use array_reduce with array_merge.

$unique = array_unique(array_reduce($multi_array_example, 'array_merge', []));

returns [1, 2, 3, 4, 5, 6]

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