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<a href="http://www.xunsearch.com" target="_blank">Xunsearch PHP-SDK</a> v1.3.2 权威指南
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	<div class="toc"><ol><li><a href="#ch0">什么是同义词搜索</a></li><li><a href="#ch1">英文同义词的特殊处理</a></li><li><a href="#ch2">管理同义词库</a></li><li><a href="#ch3">查看已有同义词库</a></li><li><a href="#ch4">使用同义词搜索功能</a></li></ol></div><h1 id="-">同义词搜索</h1>

<p>人类语言文化丰富，同一个意思有无数种不同的表达方式。因此，<strong>同义词</strong>
是全文检索中非常重要和必要的一项基础功能。从 <code>1.3.0</code> 版本起，<code>Xunsearch</code> 
开始提供同义搜索搜索功能。</p>

<h2 id="ch0">1. 什么是同义词搜索<a name="ch0" class="anchor">?</a></h2>

<p>为了更好的提升用户搜索体验，我们希望用户在搜索“浙江大学”的时候也同时匹配包含缩写“浙大”的结果，
这就是所谓的同义词搜索。通常我们说“浙大”是“浙江大学”的同义词，前者是常用缩写，后者是标准词（原词）。</p>

<p><strong>同义词搜索</strong> 完全依赖于您事先设置好的同义词库，词库内每条记录由“标准词（原词）”和“同义词”组成，
它们都必须是独立的词汇，也就是最小的索引单位，不可以是多个词组成的短语。</p>

<blockquote class="tip">
<p><strong>Tip:</strong> 独立词汇的意思对于英文来说就是一个单词，对于中文来说必须是 <code>scws</code> 词库中的一个词。<br />
  <em>Xunsearch</em> 的同义词不同于 <em>Xapian</em>，会智能进行字段匹配和转换，您只需维护通用词库。</p>
</blockquote>

<h2 id="ch1">2. 英文同义词的特殊处理<a name="ch1" class="anchor">?</a></h2>

<p>英文单词的同义词在 xunsearch 中做了一些个特殊处理：</p>

<ul>
<li><p><strong>统一小写</strong> 统一转换为小写字母进行存储，不支持必须保留大写字母的同义词。</p></li>
<li><p><strong>同根词支持</strong> 英语同一个单词有多种不同的形式，如：单复数、过去式和现在分词等。
而它们要传送的其实是同一种涵义。因此，对于纯英文的同义词记录会自动进行词根处理。
词根记录保存为大写字母 Z 开头的记录。例如：</p>

<p>设置 <code>find</code> 是 <em>search</em> 的同义词，那么检索 <em>searching</em> 时如果 <em>searching</em> 
本身没有同义词，那么也会匹配包含 <code>finding</code> 或 <code>finds</code> 等同根词的结果。</p></li>
<li><p><strong>复合词支持</strong> 支持对多个单词组成的短语设置同义词，词之间用一个半角空格分开，
但同义词仍然只允许一个单词或中文词哦。如：</p>

<p>设置 <code>您好</code> 为 <em>hello world</em> 的同义词，那么检索 <em>hello world ok</em> 
时也会匹配同时包含 <code>您好</code> 和 <code>ok</code> 的记录。</p></li>
</ul>

<h2 id="ch2">3. 管理同义词库<a name="ch2" class="anchor">?</a></h2>

<p>您可以通过 <a href="../api/XSIndex.html#addSynonym">XSIndex::addSynonym</a> 和 <a href="../api/XSIndex.html#delSynonym">XSIndex::delSynonym</a> 来添加和删除同义词记录。
多次调用这两个接口函数的时候支持使用<a href="index.buffer.html">索引缓冲区</a>来提高效率。</p>

<p>参数 <code>$raw</code> 是字符串，表示记录中的原词（标准词），<code>$synonym</code> 也是字符串，表示记录中的同义词，
对于删除操作可以省略该参数表示清空原词的所有同义词。</p>

<p>以下为示例代码，其中的 <code>$index</code> 变量是索引操作对像，参见<a href="index.overview#ch1">如何开始使用索引?</a></p>

<div class="hl-code"><div class="php-hl-main"><pre><span class="php-hl-comment">//</span><span class="php-hl-comment"> 给 &quot;搜索&quot; 增加 &quot;检索&quot; &quot;查找&quot; 两个同义词</span>
<span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">addSynonym</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">搜索</span><span class="php-hl-quotes">'</span><span class="php-hl-code">, </span><span class="php-hl-quotes">'</span><span class="php-hl-string">检索</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
</span><span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">addSynonym</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">搜索</span><span class="php-hl-quotes">'</span><span class="php-hl-code">, </span><span class="php-hl-quotes">'</span><span class="php-hl-string">查找</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 给 &quot;Hello world&quot; 增加同义词 &quot;你好&quot;</span>
<span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">addSynonym</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">hello world</span><span class="php-hl-quotes">'</span><span class="php-hl-code">, </span><span class="php-hl-quotes">'</span><span class="php-hl-string">你好</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 删除 search 的全部同义词</span>
<span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">delSynonym</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">search</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 删除 &quot;搜索&quot; 的同义词 &quot;检索&quot;</span>
<span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">delSynonym</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">搜索</span><span class="php-hl-quotes">'</span><span class="php-hl-code">, </span><span class="php-hl-quotes">'</span><span class="php-hl-string">检索</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;</span></pre></div></div>

<p>除了调用 <code>API</code>　外，您还可以使用 <a href="util.indexer#ch8">Indexer 索引管理工具</a> 进行同义词管理。</p>

<h2 id="ch3">4. 查看已有同义词库<a name="ch3" class="anchor">?</a></h2>

<p>通过 <a href="../api/XSSearch.html#getAllSynonyms">XSSearch::getAllSynonyms</a> 来获取当前索引库内的全部同义词记录，返回一个数组，
以原词（标准词）为键，其同义词列表为值。</p>

<p>以下为示例代码，其中的 <code>$search</code> 变量是搜索操作对像，参见<a href="search.overview#ch1">如何开始使用搜索?</a></p>

<div class="hl-code"><div class="php-hl-main"><pre><span class="php-hl-comment">//</span><span class="php-hl-comment"> 获取当前库的前 100 个同义词记录</span>
<span class="php-hl-var">$synonyms</span><span class="php-hl-code"> = </span><span class="php-hl-var">$search</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">getAllSynonyms</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 获取当前库第 6~15 条同义词记录</span>
<span class="php-hl-var">$synonyms</span><span class="php-hl-code"> = </span><span class="php-hl-var">$search</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">getAllSynonyms</span><span class="php-hl-brackets">(</span><span class="php-hl-number">10</span><span class="php-hl-code">, </span><span class="php-hl-number">5</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 查看包含隐藏同义词根在内的前 20 条记录</span>
<span class="php-hl-var">$synonyms</span><span class="php-hl-code"> = </span><span class="php-hl-var">$search</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">getAllSynonyms</span><span class="php-hl-brackets">(</span><span class="php-hl-number">20</span><span class="php-hl-code">, </span><span class="php-hl-number">0</span><span class="php-hl-code">, </span><span class="php-hl-reserved">true</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;</span></pre></div></div>

<p>除了调用 <code>API</code>　外，您还可以使用 <a href="util.quest#ch2">Quest 搜索工具</a> 进行同义词管理。</p>

<h2 id="ch4">5. 使用同义词搜索功能<a name="ch4" class="anchor">?</a></h2>

<p>同义词搜索默认是不开启的，如果您打算使用同义词搜索，这部分功能隶属于<a href="search.query.html">构建搜索语句</a>。</p>

<p>在设置查询语句 <a href="../api/XSSearch.html#setQuery">XSSearch::setQuery</a> 之前调用 <a href="../api/XSSearch.html#setAutoSynonyms">XSSearch::setAutoSynonyms</a> 来开启同义词功能。</p>

<div class="hl-code"><div class="php-hl-main"><pre><span class="php-hl-comment">//</span><span class="php-hl-comment"> 假设”搜索“有且仅有一个同义词”检索“</span>
<span class="php-hl-comment">//</span><span class="php-hl-comment"> 开启同义词搜索，输出：</span>
<span class="php-hl-comment">//</span><span class="php-hl-comment"> Xapian::Query(((搜索:(pos=1) SYNONYM 检索:(pos=89)) AND 世界:(pos=2)))</span>
<span class="php-hl-var">$search</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">setAutoSynonyms</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">setQuery</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">搜索世界</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">getQuery</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 开启同义词搜索，并带有字段效果，假设 subject 是项目的第二个字段，输出：</span>
<span class="php-hl-comment">//</span><span class="php-hl-comment"> Xapian::Query(((B搜索:(pos=1) SYNONYM B检索:(pos=89)) AND B世界:(pos=2)))</span>
<span class="php-hl-var">$search</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">setAutoSynonyms</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">setQuery</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">subject:搜索世界</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">getQuery</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 关闭同义词搜索，输出：</span>
<span class="php-hl-comment">//</span><span class="php-hl-comment"> Xapian::Query((搜索:(pos=1) AND 世界:(pos=2)))</span>
<span class="php-hl-var">$search</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">setAutoSynonyms</span><span class="php-hl-brackets">(</span><span class="php-hl-reserved">false</span><span class="php-hl-brackets">)</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">setQuery</span><span class="php-hl-brackets">(</span><span class="php-hl-quotes">'</span><span class="php-hl-string">搜索世界</span><span class="php-hl-quotes">'</span><span class="php-hl-brackets">)</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">getQuery</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;</span></pre></div></div>

<blockquote class="tip">
<p><strong>Tip:</strong> 您可以分别在开启/关闭同义词功能的条件下，对比 <a href="../api/XSSearch.html#getQuery">XSSearch::getQuery</a> 查询语句分析结果。</p>
</blockquote>

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