gistfile1.php

<?php
     ini_set("memory_limit","500M");
     date_default_timezone_set('Asia/Shanghai');
     ini_set('max_execution_time',300000);
     echo "<pre />";
     $array=array();
     $data=array();
     $file=fopen('2013-11-19.csv','r');
     while($re=fgets($file)){
          $arr=explode(",",$re);
          $array[$arr[1]][]=$arr[0];
     }

    foreach($array as $key=>$val){
       if(count($val)>=5){
            $data[$key]=$val;
       }
    }
    echo count($data)."<br />";
    print_r($data);