


Of course, this article is not to do research on Chinese search engines, but to share how to use PHP to build an on-site search engine. This article is an article in this system.
The word segmentation tool I use is the open source version of ICTCLAS from the Institute of Computing Technology, Chinese Academy of Sciences. There is also the open source Bamboo, which I will also investigate later.
It is a good choice to start from ICTCLAS, because its algorithm is widely spread, has public academic documents, is easy to compile, and has few library dependencies. But currently only C/C++, Java and C# versions of the code are provided, and there is no PHP version of the code. What should we do? Maybe we can study its C/C++ source code and academic documents, and then develop a PHP version. However, I want to use inter-process communication to call the C/C++ version of the executable file from the PHP code.
After downloading and decompressing the source code, directly make ictclas on a machine with C++ development library and compilation environment. There is an error in its Makefile script, and the code that executes the test does not add '. /', of course it cannot be executed successfully like under Windows. But it does not affect the compilation results.
The PHP class for Chinese word segmentation is below. Use the proc_open() function to execute the word segmentation program, interact with it through the pipeline, input the text to be segmented, and read the word segmentation results.
class NLP{
private static $cmd_path;
// Does not end with '/'
static function set_cmd_path($path){
self::$cmd_path = $path;
}
private function cmd($str){
$descriptorspec = array(
0 => array("pipe", "r"),
1 => array("pipe", "w"),
);
$cmd = self::$cmd_path . "/ictclas";
$process = proc_open($cmd, $descriptorspec, $pipes);
if (is_resource($process)) {
$str = iconv('utf-8', 'gbk', $str);
fwrite($pipes[0], $str);
$output = stream_get_contents($pipes[1]);
fclose($pipes[0]);
fclose($pipes[1]);
$return_value = proc_close($process);
}
/*
$cmd = "printf '$input' | " . self::$cmd_path . "/ictclas";
exec($cmd, $output, $ret);
$output = join("n", $output);
*/
$output = trim($output);
$output = iconv('gbk', 'utf-8', $output);
return $output;
}
/**
* Perform word segmentation and return a word list.
*/
function tokenize($str){
$tokens = array();
$output = self::cmd($input);
if( $output){
$ps = preg_split('/s+/', $output);
foreach($ps as $p){
list($seg, $tag) = explode('/ ', $p);
$item = array(
'seg' => $seg,
'tag' => $tag,
);
$tokens[] = $item;
}
}
return $tokens;
}
}
NLP::set_cmd_path(dirname(__FILE__));
?>
It is very simple to use (make sure the ICTCLAS compiled executable and dictionary are in the current directory):
require_once('NLP.php');
var_dump(NLP::tokenize('Hello, World!'));
?>

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。


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