如何在循环中使用array_filter

Question

I want to filter the data from the array in a loop. All i want to know is can I use the array_filter inside loop because i am using it and it is not working properly This is the array which i am getting from DB

   Array
    (
        [0] => Chocolate Manufacturers,C
        [1] => ,,,Chocolate Manufacturers,,Chocolate Manufacturers,,Chocolate Manufacturers
        [2] => 
    )

I am making the array unique by using this code

$num = 2;
for($i=0;$i<count($listing);$i++){

    //echo var_export($listing[$i]->cat_title).'<br>';
    $listing_cat[$i] = rtrim(ltrim($listing[$i]->cat_title,','),',');
    $listing_cat[$i] = explode(',', $listing_cat[$i]);
    //$listing_cat[$i] = array_filter(array_keys($listing_cat[$i]), function ($k){ return strlen($k)>=3; });
    $listing_cat[$i] = array_filter($listing_cat[$i], function ($sentence){
        //divide the each sentence in words
        $words = explode(',',$sentence);
        $resSentence = [];
        //check each words if their length is more then $num
        foreach($words as $word){
            if(strlen($word) > $num){
                $resSentence[] = $word;
            }
        }
        return implode(' ', $resSentence);
    });
    $listing_cat[$i] = array_unique($listing_cat[$i]);

    $listing_cat[$i] = implode(',', $listing_cat[$i]);
    $listing_cat[$i] = rtrim(ltrim($listing_cat[$i],','),',');
    //$tags['title'][$i] = rtrim(ltrim($listing[$i]->cat_title,','),',');
}

After running this code result is showing like this

   Array (
    [0] => Chocolate Manufacturers,C
    [1] => Chocolate Manufacturers
    [2] => 
   )

But what i want is to remove the C from the first array i mean to say the unwanted string or string which length will be less than 2 i want to remove that.

Expected Result:

Array (
        [0] => Chocolate Manufacturers
        [1] => Chocolate Manufacturers
        [2] => 
       )

i used the below function to remove

$NUM = 2;
$listings[$i] = array_filter($listings[$i], function ($element){ 
        return ($element[$i] > $NUM);
        }); 

But i think because it is in loop it is not working properly. I am placing this code above the array_unique line in loop. All i want is to remove the value which length will be less than 2.

Finally i have achieved my desired answer

    $num = 2;

for ($i = 0; $i < count($listing); $i++) {
    //$listing_cat[$i] = array_unique($listing[$i]->cat_title);
    $listing_cat[$i] = rtrim(ltrim($listing[$i]->cat_title, ','), ',');

    $sentence = $listing_cat[$i];

    //divide the each sentence in words
    $words = explode(',', $sentence);
    $resSentence = [];

    //check each words if their length is more then $num
    foreach ($words as $word) {
        if (strlen($word) > $num) {
            $resSentence[] = $word;
        }
    }
    $listing_cat[$i] = array_unique($resSentence);

    $listing_cat[$i] = implode(',',$listing_cat[$i]);

    $listing_cat[$i] = rtrim(ltrim($listing_cat[$i],','),',');
}

echo '<pre>';
print_r($listing_cat);
echo '</pre>';

it is showing perfect result what i want

Array (
        [0] => Chocolate Manufacturers
        [1] => Chocolate Manufacturers
        [2] => 
       )

Thanks all for help really appriciated

Answer 1

First of all: I recommend you not to use $listing along with $listings as variable names as it can easily lead to confusion and is not a good readability (especially confusing here on StackOverflow).

Then: You have an error in your code. You are not checking for the length (count) but for the string itself which does resolve in TRUE.

You have:

$NUM = 2;

$listings[$i] = array_filter($listings[$i], function ($element){ 
    return ($element[$i] > $NUM);
    }
); 

You should have:

$NUM = 2;

$listings[$i] = array_filter($listings[$i], function ($element) use ($NUM) { 
    return (strlen($element[$i]) >= $NUM);
    }
);