信息检索课程实验：构建索引并实现对文档集合的检索

<?php
    $_txts = array('1.txt','2.txt','3.txt');
    $_len = count($_txts);
    for ($i = 0;$i < $_len;$i++){
        $_contents[] = file_get_contents($_txts[$i]);
    }
         
    for ($i = 0;$i < $_len;$i++){
        //分词
        $_words[] = explode(' ',trim($_contents[$i]));
        foreach ($_words[$i] as $_key=>$_value){
            $_value = trim($_value);
            $_value = preg_replace('/[.|,|(|)|-|;]/','',$_value);
            $_words[$i][$_key]=strtolower($_value);
                 
        }
        //词频tf
        $_tf[] = array_count_values($_words[$i]);
        //去重
        $_words[$i]= array_unique($_words[$i]);
    } 
         
    //合并
    $_words_com = array_merge($_words[0],$_words[1],$_words[2]);
    //文档频率
    $_df = array_count_values($_words_com);
    //特征向量
    for ($i = 0;$i < $_len;$i++){
        $_vsm[$i] = $_df;
        foreach($_vsm[$i] as $_key=>$_value){
            $_vsm[$i][$_key] = 0;
        }
        for ($j=0;$j<count($_words[$i]);$j++){
            if (in_array($_words[$i][$j],$_words_com)){
                $_vsm[$i][($_words[$i][$j])] = ($_tf[$i][($_words[$i][$j])])*(log($_len/$_df[($_words[$i][$j])]));
                     
            } 
        }
    } 
         
    for($i = 0;$i < count($_vsm); $i++){
        echo '第'.($i+1).'篇文档的特征向量: ('. implode(",",$_vsm[$i]).')<br/>';
    }
         
    //测试
    $_query = 'java';
    $_vsm_que = $_df;
    foreach($_vsm_que as $_key=>$_value){
        $_vsm_que[$_key] = 0;
    }
    if (in_array($_query,$_vsm_que)){
        $_vsm_que[$_query] = 1;
    }
         
    for ($i = 0; $i < count($_vsm); $i++){
        foreach($_vsm_que as $_key=>$_value){
            $_sim[$i] += ($_vsm[$i][$_key]) * ($_vsm_que[$_key]);
            $_w1 += pow($_vsm_que[$_key],2);
            $_w2 += pow($_vsm[$i][$_key],2);
        }
        //求夹角余弦值
        $_cos[$i] = $_sim[$i]/(sqrt($_w1)*sqrt($_w2));
    }
         
    arsort($_cos);
    foreach($_cos as $_key=>$_value){
        echo '最符合的结果为第'.($_key+1).'篇文档';
             
        break;
    }
?>