Es estrazione gi,pdb da fasta

<?php
$s=file_get_contents("actin-human.fasta");
$righe=explode("\n",$s);
$string1="gaattg";
$gi_regexp="/^>gi\|(\d{5,12})\|/";
$pdb_regexp="/\|pdb\|(\w+)\|/";
$array_gi=array();
$array_pdb=array();
$i=0;
$j=0;

foreach($righe as $riga){
  $riga=trim($riga);
  if(preg_match($gi_regexp,$riga,$matches)){
      array_push($array_gi,$matches[1]);
      $i++;
}
  if(preg_match($pdb_regexp,$riga,$matches)){
      array_push($array_pdb,$matches[1]);
      $j++;
}
}
echo "<p>trovati $i gi</p><p>";
echo "trovati $j pdb</p><p>";
echo "i gi trovati sono:</p><p>";
foreach($array_gi as $gi){
  echo $gi."<br>";
}
echo "i pdb trovati sono:</p><p>";
foreach($array_pdb as $pdb){
  echo $pdb."<br>";
}
?>