collections &#39;remove&#39; method ?

https://laravel.com/docs/8.x/collections#method-replace

Level 73

You can use replace or slice

https://laravel.com/docs/8.x/collections#method-slice

Level 39

Hi @tray2

Clearly not slice

and I don't see (for the moment) how to use replace (for that), I give an other example of expected result below?

$col1=collect(['a','a','2','3','3','4']);
$col2=collect(['a','3']);

expected result : ['a','2','3','4']

newbie360

Level 24

$col1->concat($col2)->unique()->dd();

Level 39

Hi @newbie360

Ok for test2, but does not pass test 1 (unique cannot be used)

newbie360

Level 24

hmm no idea xD this never happened in my project

bestmomo

Level 52

Hello,

Try that :

$unique = $col1->unique();
$result = $col1->diffKeys($unique)->concat($unique->diff($col2));

Level 39

Hi @bestmomo

Thanks for your try, it passed the 2 tests but not this 3rd one

Test n°3
$col1=collect(['a','a','2','2','3','3','4']);
$col2=collect(['a','2','2']);

// expected result : ['a','3','3','4']

I want to remove (one to one removal) from col1 all values present in col2

The pseudo code with foreach should be

foreach v2 in col2
	i1 = index of first (or last, ...) value v2 in col1
	if exists i1 then remove col1[i1]

Level 80

That makes no sense though, because you say you want to remove from $col1 all values present in $col2. Well, “a” is present in $col2 but then you’re expecting that to still be present?

So, it might be better if you just told us what you’re actually trying to achieve instead of these contrived examples that contradict what you’re saying. Give us some context.

Level 39

Hi @martinbean

Did you read my last post (with the pseudo code)?

Level 80

@sr57 Yes, and like I say, what you described you wanted is different to what you listed as the expected result!

you say you want to remove from $col1 all values present in $col2. Well, “a” is present in $col2 but then you’re expecting that to still be present?

So let’s stop talking “pseudo” code and just tell us what you’re actually trying to do.

Level 39

because you say you want to remove from $col2 all values present in $col2

I never said this, neither I wrote this.

I wrote this

I want to remove (one to one removal) from col1 all values present in col2

Level 80

@sr57 Yes. And “a” is present in col2 so should, by your logic, be removed. But then you say you’re expecting it to still be there?

Again, just tell us what you’re trying to do. Stop with the pseudo code nonsense, and then we can get to a solution faster.

Level 39

Communication is a difficult art :-)

'a' is present 2 times ins col1, and only one in col2, so with the logic I want it remains one in col1

Let's imagine col1 is a fridge with aliments and you eat some define in col2

Level 80

I’m not interested in “imagining” or messing about with pseudo code. Why can’t you just tell us what the problem is so we can help you get to the answer?

I want to remove (one to one removal) from col1 all values present in col2

Again, “a” is in col2, so by your logic should be removed.

Level 39

???

If there is 2 yogurts in the fridge and I eat one, it remains 1 yogurt in the fridge.

If you don't understand this, don't (want to) understand pseudo-code, ... I have no other idea.

Level 80

@sr57 I’m only going on what YOU have said.

I want to remove (one to one removal) from col1 all values present in col2

“a” is in col2 in your example. Therefore “a” should be removed.

PHP doesn’t discern between two strings with the value of “a”. They both have the same value as far as PHP is concerned. So if you say, “remove a”, then PHP is going to remove anything with the value of “a”.

So, either refactor your code to use actual entities that have identities so that entities with the same value can be distinguished between. Or show us your actual code and problem.

Your persistence in abstracting the problem with pseudo code and analogies is only making for it to take longer and expend more effort than needed to get to the actual solution.

Best Answer

Level 75

@sr57 Working code is this

$col1 = collect(['a','a','2','3','3','4']);

$col2 = collect(['a', '2']);

$copy = clone $col2;

$result = $col1->map(function ($item) use ($copy) {
    if (in_array($item, $copy->toArray())) {
        $key = $copy->search(function ($value) use ($item) {
            return $value == $item;
        });

        $copy->pull($key);

        return;
    }
        
    return $item;
})->filter()->values()->toArray();

// result -> ['a', '3', '3', '4']

Or (it's almost same)

$col1 = collect(['a','a','2','3','3','4']);

$col2 = collect(['a', '2']);

$copy = clone $col2;

$result = $col1->map(function ($item) use ($copy) {
    if ($copy->contains($item)) {
        $key = $copy->search(function ($value) use ($item) {
            return $value == $item;
        });

        $copy->forget($key);
      
        return;
    } 
  
    return $item;
})->filter()->values()->toArray();

// result -> ['a', '3', '3', '4']

Level 39

Thanks @michaloravec

Your code passed the 3 tests.

But really not so clear/simple as a foreach loop (as given in my pseudo-code), an other solution should be in 'plain php' to count the nb per elts in both collections, do the subtraction and recreate the array/collection at the end.

I'll implement your code and mine to see in term of time consumption ... to be continued.

If sb else fond a better solution, let's know.

Level 75

map() use foreach behind the scene.

So I don't know why you have still a problem with my code...

Level 39

@michaloravec

map() use foreach behind the scene.

I know

I don't know why you have still a problem with my code...

I did not write this

Level 39

For your information @michaloravec @tray2 @newbie360 @bestmomo @martinbean

Duration bench (with my data)

Php foreach* : 1

@michaloravec method 1 : ~4 times more

@michaloravec method 2 : ~3 times more

*like given pseudo code ( fridge for @martinbean :-) )

	private function col_remove1($col1,$col2) {
	# inputs : 2 collections
	# output  : collection = col1 - col2
		$c1=clone $col1;
		foreach ($col2 as $e ) {
		$i=$c1->search($e);
			if ( false !== $i ) {
				$f=$c1->pull($i);
			}
		}
		$c1=$c1->values();
		return $c1;
	}

Level 75

Do you understand to yourself?

Level 80

…and we could maybe help you arrive at a more performant solution if you just showed us the actual problem.

Level 39

@michaloravec

changed worse to more

hope you understand better ...

Level 80

FFS, just tell us what the frigging problem is! You’re going to get shitty answers if you don’t actually share with us all of the details of your bloody problem!

Why are you so hesitant in showing us the actual issue?

Level 39

https://laracasts.com/discuss/channels/laravel/laravel-sanitary-check

From the beginning there no problem, this post has a best answer if you ant to do better tha, @michaloravec just propose your solution.

That said, this post has no answer yet

Level 75

@sr57 What do you want to say with a link to another thread?

levitorres

Level 1

I also have the same question. I followed everything and it seems like its not working in my case. Hopefully someone can post an alternative way of fixing the issue. Thanks.