比较数组，直到有唯一的数组

Question

I have the following multidimensional array called $existing_combinations

Array
(
    [0] => Array
        (
            [1] => 6
            [2] => 7
            [3] => 9
        )

    [1] => Array
        (
            [1] => 1
            [2] => 21
            [3] => 9
        )

    [2] => Array
        (
            [1] => 1
            [2] => 7
            [3] => 9
        )

)

I then generate a new array ( $new_combination ) which has a combination of the same set of values. Example:

Array
(
    [1] => 6
    [2] => 21
    [3] => 9
)

I then test if $new_combination exists in $existing_combinations with the following in the hope that I will end with a unique combination in $new_combination :

foreach($existing_combinations as $key => $combination){
    while($new_combination == $combination){
        $new_combination = generateNewCombination();
    }
}

The problem is that if $new_combination matches an array that is not at index 0, then when I generate a new combination I am at risk of this matching a $combination that has already been tested against (and will not be tested again).

Sorry if this is a simple one but I'm struggling to think of how I can ensure $new_combination will always end up unique.

Any ideas?

Thanks

Answer 1

You can use in_array in this case, because php compares arrays as value. So, the code can be:

while(in_array($new_combination = generateNewCombination(), $existing_combinations));

print_r($new_combination);

Answer 2

I wrote the below before realizing that in_array can also see if an array exists within an array. So you can simply do this:

if (!in_array($new_combination, $existing_combinations)) {
    // It's unique.
}

In the below outdated bit, see the note on using sort , if a different sequence of the same numbers isn't considered unique for your purposes.

---

[ For Entertainment ]

May not be the most elegant way around, but I would simply do this to keep it simple:

$combo_hashes = [];

// Implode the existing combos into strings.
foreach($existing as $vals) {
    $combo_hashes[] = implode(':', $vals);
}

Then, all you need to check with your new combo is:

// Check if the "hash"-string already exists.

if (!in_array( implode(':', $new_combo), $combo_hashes)) {
    // ... and we're unique.
}

This presumes that you consider [1,3,2] different from [2,1,3] . If they are equivalent (I don't know what your use case is), you should sort($vals); before you generate the check-strings.

Answer 3

合并所有第二级数组，然后运行array_unique（）摆脱重复的值。