为什么停止删除单词是空的？ （PHP）

Question

I'm the beginner NLP programmer in PHP. I just want to discuss about the stop word removal.

this is my practice:

I have the following declaration of a variable $words = "he's the young man";

and then I remove the common words like this

 $common_words = $this->common_words();
 $ncwords = preg_replace('/\b('.implode('|',$common_words).')\b/','',$data); 
 // I have save the array common_words in another function

and I explode my no common words

$a_ncwords=explode(" ", $ncwords);

But, when I print $a_ncwords, like so print_r($a_ncwords);

I get a result like this:

Array ( [0] => [1] => [2] => young [3] => man )

why are the index[0] and index[1] array values null?

Answer 1

Remove the empty array elements.

To appease those who said it didn't answer your question:

Your preg_replace is replacing words with null and when you explode because your regex is off, those null values are getting created in your array $a_ncwords when you explode.

$a_ncwords = array_filter($a_ncwords);