Js Remove Non Unique or Unique Array Values

Remove array values that appear more than once and remove all values that appear only once

// remove all values that appear more than once
const removeNonUnique = arr =>
  [...new Set(arr)].filter(i => arr.indexOf(i) === arr.lastIndexOf(i));

removeNonUnique([1, 2, 2, 3, 4, 4, 5]); // [1, 3, 5]

// remove all values that appear only once
const removeUnique = arr =>
  [...new Set(arr)].filter(i => arr.indexOf(i) !== arr.lastIndexOf(i));

removeUnique([1, 2, 2, 3, 4, 4, 5]); // [2, 4]

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PHP Sorting an array by multiple fields

sort multiple arrays or an array of associative arrays by different fields using array_multisort.

// Sorting an array by multiple fields
$people = [
    ['name' => 'John', 'age' => 28, 'city' => 'New York'],
    ['name' => 'Alice', 'age' => 24, 'city' => 'Los Angeles'],
    ['name' => 'Bob', 'age' => 32, 'city' => 'Chicago'],
    ['name' => 'Charlie', 'age' => 24, 'city' => 'San Francisco']
];

// Create arrays for the fields you want to sort by
$age = array_column($people, 'age');
$name = array_column($people, 'name');

// Use array_multisort to sort by age (ascending) and then by name (ascending)
array_multisort($age, SORT_ASC, $name, SORT_ASC, $people);

print_r($people);

// output
Array
(
    [0] => Array
        (
            [name] => Alice
            [age] => 24
            [city] => Los Angeles
        )

    [1] => Array
        (
            [name] => Charlie
            [age] => 24
            [city] => San Francisco
        )

    [2] => Array
        (
            [name] => John
            [age] => 28
            [city] => New York
        )

    [3] => Array
        (
            [name] => Bob
            [age] => 32
            [city] => Chicago
        )
)

// Sorting by multiple fields with different sort orders
$people = [
    ['name' => 'John', 'age' => 28, 'city' => 'New York'],
    ['name' => 'Alice', 'age' => 24, 'city' => 'Los Angeles'],
    ['name' => 'Bob', 'age' => 32, 'city' => 'Chicago'],
    ['name' => 'Charlie', 'age' => 24, 'city' => 'San Francisco']
];

// Create arrays for age and name
$age = array_column($people, 'age');
$name = array_column($people, 'name');

// Sort by age descending and by name ascending
array_multisort($age, SORT_DESC, $name, SORT_ASC, $people);

print_r($people);

// output
Array
(
    [0] => Array
        (
            [name] => Bob
            [age] => 32
            [city] => Chicago
        )

    [1] => Array
        (
            [name] => John
            [age] => 28
            [city] => New York
        )

    [2] => Array
        (
            [name] => Alice
            [age] => 24
            [city] => Los Angeles
        )

    [3] => Array
        (
            [name] => Charlie
            [age] => 24
            [city] => San Francisco
        )
)

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