Text tool to get useful keywords to describe it

keywords.php

<div style="width:550px">
<form method="POST">
<textarea name="text" style="width:100%" rows="20"><?=($_POST['text'])?$_POST['text']:''?></textarea>
<input type="submit"/>

<pre>
<?php
function keywords1($text){
	$text = preg_replace('/[\!-@\[-\x60\x7b\x7e]/',' ',mb_strtolower($text,'UTF-8'));
	$text = preg_replace('/\s+/',' ',$text);
	var_dump($text);
	foreach(explode(' ',$text) as $key)$count[$key]++;
	foreach($count as $key=>$value)$length[$key] = mb_strlen($key,'UTF-8');
	asort($count,1);
	arsort($length);
	$count = array_slice($count, 0, round(count($count)/2));
	$length = array_slice($length, 0, round(count($length)/2));
//	$count = array_slice($count, round(count($count)/3), round(count($count)/3) - round(count($count)/2));
//	$length = array_slice($length, round(count($length)/3), round(count($length)/3) - round(count($length)/2));
	//var_dump($count);
	//var_dump($length);

	$keywords = array_intersect(array_keys($count),array_keys($length));
	$keywords = array_slice($keywords, 0, 5);
//	$keywords = array_slice($keywords, round(count($keywords)/3), round(count($keywords)/3) - round(count($keywords)/2));
	var_dump($keywords);
	return $keywords;
}

function keywords($text, $max=5){
	$text = preg_replace('/[\!-@\[-\x60\x7b\x7e]/',' ',mb_strtolower($text,'UTF-8'));
	$text = preg_replace('/\s+/',' ',$text);
	foreach(explode(' ',$text) as $key)$count[$key]++;
	foreach($count as $key=>$value)$length[$key] = mb_strlen($key,'UTF-8');
	asort($count,1);
	arsort($length);
	$count = array_slice($count, 0, round(count($count)/2));
	$length = array_slice($length, 0, round(count($length)/2));
	$keywords = array_intersect(array_keys($count),array_keys($length));
	$keywords = array_slice($keywords, 0, $max);
	return $keywords;
}


$keywords = ($_POST['max'])?keywords($_POST['text'],$_POST['max']):keywords($_POST['text']);
echo '</pre><input value="'.implode(', ',$keywords).'" style="width:90%"/><input type="number" name="max" style="width:9%" value="'.$_POST['max'].'" step="1"/></form></div>';

letter_count.php

<?php
if(@$a = @$_POST?:$_GET){
  $a = strip_tags(trim(@current($a)?:key($a)));
  echo $a.'<br/>';
  echo 'Кол. символов: '.mb_strlen($a,'UTF-8').'<br/>';
}else{
  echo '<form method="post"><textarea name="a"></textarea><input type="submit"/></form>';
}