{"id":112444,"date":"2026-10-03T17:16:52","date_gmt":"2026-10-03T09:16:52","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/112444.html"},"modified":"2026-10-03T17:16:52","modified_gmt":"2026-10-03T09:16:52","slug":"nlp%e5%9f%ba%e7%a1%80%e5%88%b0%e9%ab%98%e7%ba%a702%ef%bc%9a%e8%af%8d%e8%a2%8b%e6%a8%a1%e5%9e%8b%e3%80%81tf-idf-%e4%b8%8e%e6%96%87%e6%9c%ac%e8%a1%a8%e7%a4%ba","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/112444.html","title":{"rendered":"NLP\u57fa\u7840\u5230\u9ad8\u7ea702\uff1a\u8bcd\u888b\u6a21\u578b\u3001TF-IDF \u4e0e\u6587\u672c\u8868\u793a"},"content":{"rendered":"<h2>\u8bcd\u888b\u6a21\u578b\u3001TF-IDF \u4e0e\u6587\u672c\u8868\u793a<\/h2>\n<p>\u5148\u8ba1\u6570&#xff0c;\u540e\u601d\u8003\u3002TF-IDF \u5728\u5b9a\u4e49\u660e\u786e\u7684\u4efb\u52a1\u4e0a\u4f9d\u7136\u80dc\u8fc7\u5d4c\u5165\u6a21\u578b&#xff0c;\u5373\u4fbf\u5728 2026 \u5e74\u3002<\/p>\n<p>\u7c7b\u578b&#xff1a; \u6784\u5efa<br \/>\n\u8bed\u8a00&#xff1a; Python<br \/>\n\u524d\u7f6e\u6761\u4ef6&#xff1a; Phase 5 \u00b7 01 (\u6587\u672c\u5904\u7406)&#xff0c;Phase 2 \u00b7 02 (\u4ece\u96f6\u5b9e\u73b0\u7ebf\u6027\u56de\u5f52)<br \/>\n\u7528\u65f6&#xff1a; ~75 \u5206\u949f<\/p>\n<h3>\u95ee\u9898\u6240\u5728<\/h3>\n<p>\u6a21\u578b\u9700\u8981\u6570\u5b57&#xff0c;\u800c\u4f60\u53ea\u6709\u5b57\u7b26\u4e32\u3002<\/p>\n<p>\u6bcf\u4e2a NLP \u7ba1\u9053\u90fd\u5fc5\u987b\u56de\u7b54\u540c\u4e00\u4e2a\u95ee\u9898&#xff1a;\u5982\u4f55\u5c06\u53d8\u957f\u7684 token \u6d41\u8f6c\u5316\u4e3a\u5206\u7c7b\u5668\u53ef\u4ee5\u6d88\u8d39\u7684\u56fa\u5b9a\u5927\u5c0f\u5411\u91cf\u3002\u8fd9\u4e2a\u9886\u57df\u7ed9\u51fa\u7684\u7b2c\u4e00\u4e2a\u7b54\u6848\u662f\u80fd\u7528\u7684\u6700\u7b28\u65b9\u6848\u2014\u2014\u6570\u8bcd\u9891&#xff0c;\u6784\u9020\u6210\u5411\u91cf\u3002<\/p>\n<p>\u8fd9\u4e2a\u5411\u91cf\u627f\u8f7d\u4e86\u6bd4\u4efb\u4f55\u5d4c\u5165\u6a21\u578b\u90fd\u591a\u7684\u751f\u4ea7\u7ea7 NLP \u5e94\u7528\u3002\u5783\u573e\u90ae\u4ef6\u8fc7\u6ee4\u5668\u3001\u4e3b\u9898\u5206\u7c7b\u5668\u3001\u65e5\u5fd7\u5f02\u5e38\u68c0\u6d4b\u3001\u641c\u7d22\u6392\u5e8f&#xff08;\u5728 BM25 \u4e4b\u524d&#xff09;\u3001\u7b2c\u4e00\u6ce2\u60c5\u611f\u5206\u6790\u3001\u5b66\u672f\u754c NLP \u57fa\u51c6\u6d4b\u8bd5\u7684\u5934\u5341\u5e74\u30022026 \u5e74\u7684\u4ece\u4e1a\u8005\u5728\u7a84\u5206\u7c7b\u4efb\u52a1\u4e0a\u4ecd\u7136\u4f1a\u9996\u5148\u9009\u62e9\u5b83\u3002\u5b83\u5feb\u901f\u3001\u53ef\u89e3\u91ca&#xff0c;\u5728\u8bcd\u7684\u51fa\u73b0\u4e0e\u5426\u662f\u5173\u952e\u56e0\u7d20\u7684\u4efb\u52a1\u4e0a&#xff0c;\u5f80\u5f80\u4e0e 4 \u4ebf\u53c2\u6570\u7684\u5d4c\u5165\u6a21\u578b\u96be\u4ee5\u533a\u5206\u3002<\/p>\n<p>\u672c\u8bfe\u4ece\u96f6\u6784\u5efa\u8bcd\u888b\u6a21\u578b\u548c TF-IDF&#xff0c;\u7136\u540e\u5c55\u793a scikit-learn \u5982\u4f55\u7528\u4e09\u884c\u4ee3\u7801\u5b8c\u6210\u540c\u6837\u7684\u5de5\u4f5c&#xff0c;\u6700\u540e\u6307\u51fa\u8ba9\u4f60\u8f6c\u5411\u5d4c\u5165\u6a21\u578b\u7684\u5931\u8d25\u6a21\u5f0f\u3002<\/p>\n<h3>\u6838\u5fc3\u6982\u5ff5<\/h3>\n<p>\u8bcd\u888b\u6a21\u578b (Bag of Words, BoW) \u4e22\u5f03\u4e86\u8bcd\u5e8f\u3002\u5bf9\u6bcf\u4e2a\u6587\u6863&#xff0c;\u7edf\u8ba1\u6bcf\u4e2a\u8bcd\u6c47\u8868\u4e2d\u8bcd\u51fa\u73b0\u7684\u6b21\u6570\u3002\u5411\u91cf\u957f\u5ea6\u7b49\u4e8e\u8bcd\u6c47\u8868\u5927\u5c0f&#xff0c;\u4f4d\u7f6e i \u5b58\u653e\u8bcd i \u7684\u8ba1\u6570\u3002<\/p>\n<p>TF-IDF \u5bf9 BoW \u8fdb\u884c\u91cd\u65b0\u52a0\u6743\u3002\u51fa\u73b0\u5728\u6bcf\u4e2a\u6587\u6863\u4e2d\u7684\u8bcd\u4fe1\u606f\u91cf\u4f4e&#xff0c;\u6240\u4ee5\u7f29\u5c0f\u5176\u6743\u91cd&#xff1b;\u5728\u6574\u4e2a\u8bed\u6599\u5e93\u4e2d\u7a00\u5c11\u4f46\u5728\u5355\u4e2a\u6587\u6863\u4e2d\u9891\u7e41\u51fa\u73b0\u7684\u8bcd\u662f\u4fe1\u53f7&#xff0c;\u6240\u4ee5\u653e\u5927\u5176\u6743\u91cd\u3002<\/p>\n<p>TF-IDF(w, d) &#061; TF(w, d) * IDF(w)<br \/>\n             &#061; count(w in d) \/ |d| * log(N \/ df(w))<\/p>\n<p>\u5176\u4e2d TF \u662f\u6587\u6863\u4e2d\u7684\u8bcd\u9891&#xff0c;df \u662f\u6587\u6863\u9891\u7387&#xff08;\u5305\u542b\u8be5\u8bcd\u7684\u6587\u6863\u6570\u91cf&#xff09;&#xff0c;N \u662f\u6587\u6863\u603b\u6570\u3002log \u4f7f\u65e0\u5904\u4e0d\u5728\u7684\u8bcd\u7684\u6743\u91cd\u4fdd\u6301\u6709\u754c\u3002<\/p>\n<p>\u5173\u952e\u7279\u6027&#xff1a;\u4e24\u8005\u90fd\u4ea7\u751f\u5177\u6709\u53ef\u89e3\u91ca\u8f74\u7684\u7a00\u758f\u5411\u91cf\u3002\u4f60\u53ef\u4ee5\u67e5\u770b\u8bad\u7ec3\u597d\u7684\u5206\u7c7b\u5668\u7684\u6743\u91cd&#xff0c;\u8bfb\u51fa\u54ea\u4e9b\u8bcd\u5c06\u6587\u6863\u63a8\u5411\u5404\u4e2a\u7c7b\u522b\u3002\u4f60\u65e0\u6cd5\u7528 768 \u7ef4\u7684 BERT \u5d4c\u5165\u505a\u5230\u8fd9\u4e00\u70b9\u3002<\/p>\n<h3>\u52a8\u624b\u6784\u5efa<\/h3>\n<h4>\u6b65\u9aa4 1&#xff1a;\u6784\u5efa\u8bcd\u6c47\u8868<\/h4>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">build_vocab<\/span><span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    vocab <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">{<\/span><span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> doc <span class=\"token keyword\">in<\/span> docs<span class=\"token punctuation\">:<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> token <span class=\"token keyword\">in<\/span> doc<span class=\"token punctuation\">:<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> token <span class=\"token keyword\">not<\/span> <span class=\"token keyword\">in<\/span> vocab<span class=\"token punctuation\">:<\/span><br \/>\n                vocab<span class=\"token punctuation\">[<\/span>token<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token builtin\">len<\/span><span class=\"token punctuation\">(<\/span>vocab<span class=\"token punctuation\">)<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> vocab<\/p>\n<p>\u8f93\u5165&#xff1a;\u5df2\u5206\u8bcd\u7684\u6587\u6863\u5217\u8868&#xff08;\u4efb\u4f55\u8bcd\u7ea7\u522b\u5206\u8bcd\u5668\u90fd\u53ef\u4ee5&#xff1b;\u672c\u8bfe\u7684 code\/main.py \u4f7f\u7528\u7b80\u5316\u7684\u7eaf\u5c0f\u5199\u7248\u672c&#xff09;\u3002\u8f93\u51fa&#xff1a;{word: index} \u5b57\u5178\u3002\u7a33\u5b9a\u7684\u63d2\u5165\u987a\u5e8f\u610f\u5473\u7740\u7d22\u5f15 0 \u5bf9\u5e94\u7b2c\u4e00\u4e2a\u6587\u6863\u4e2d\u7b2c\u4e00\u4e2a\u51fa\u73b0\u7684\u8bcd\u3002\u60ef\u4f8b\u5404\u4e0d\u76f8\u540c&#xff1b;scikit-learn \u6309\u5b57\u6bcd\u6392\u5e8f\u3002<\/p>\n<h4>\u6b65\u9aa4 2&#xff1a;\u8bcd\u888b\u6a21\u578b<\/h4>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">bag_of_words<\/span><span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">,<\/span> vocab<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    matrix <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">*<\/span> <span class=\"token builtin\">len<\/span><span class=\"token punctuation\">(<\/span>vocab<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">for<\/span> _ <span class=\"token keyword\">in<\/span> docs<span class=\"token punctuation\">]<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> i<span class=\"token punctuation\">,<\/span> doc <span class=\"token keyword\">in<\/span> <span class=\"token builtin\">enumerate<\/span><span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> token <span class=\"token keyword\">in<\/span> doc<span class=\"token punctuation\">:<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> token <span class=\"token keyword\">in<\/span> vocab<span class=\"token punctuation\">:<\/span><br \/>\n                matrix<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">[<\/span>vocab<span class=\"token punctuation\">[<\/span>token<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#043;&#061;<\/span> <span class=\"token number\">1<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> matrix<\/p>\n<p><span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> docs <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">[<\/span><span class=\"token string\">&#034;cat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;sat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;on&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;mat&#034;<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token string\">&#034;cat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;cat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;ran&#034;<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">]<\/span><br \/>\n<span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> vocab <span class=\"token operator\">&#061;<\/span> build_vocab<span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> bag_of_words<span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">,<\/span> vocab<span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">]<\/span><\/p>\n<p>\u884c\u662f\u6587\u6863&#xff0c;\u5217\u662f\u8bcd\u6c47\u7d22\u5f15\u3002\u6761\u76ee [i][j] \u8868\u793a&#034;\u8bcd j \u5728\u6587\u6863 i \u4e2d\u51fa\u73b0\u4e86\u591a\u5c11\u6b21&#034;\u3002\u6587\u6863 1 \u4e2d cat \u51fa\u73b0\u4e86\u4e24\u6b21&#xff0c;\u6240\u4ee5\u662f 2\u3002\u6587\u6863 0 \u4e2d ran \u6ca1\u51fa\u73b0&#xff0c;\u6240\u4ee5\u662f 0\u3002<\/p>\n<h4>\u6b65\u9aa4 3&#xff1a;\u8bcd\u9891\u4e0e\u6587\u6863\u9891\u7387<\/h4>\n<p><span class=\"token keyword\">import<\/span> math<\/p>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">term_frequency<\/span><span class=\"token punctuation\">(<\/span>doc_bow<span class=\"token punctuation\">,<\/span> doc_length<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token punctuation\">[<\/span>c <span class=\"token operator\">\/<\/span> doc_length <span class=\"token keyword\">if<\/span> doc_length <span class=\"token keyword\">else<\/span> <span class=\"token number\">0<\/span> <span class=\"token keyword\">for<\/span> c <span class=\"token keyword\">in<\/span> doc_bow<span class=\"token punctuation\">]<\/span><\/p>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">document_frequency<\/span><span class=\"token punctuation\">(<\/span>bow_matrix<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    df <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">*<\/span> <span class=\"token builtin\">len<\/span><span class=\"token punctuation\">(<\/span>bow_matrix<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> row <span class=\"token keyword\">in<\/span> bow_matrix<span class=\"token punctuation\">:<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> j<span class=\"token punctuation\">,<\/span> count <span class=\"token keyword\">in<\/span> <span class=\"token builtin\">enumerate<\/span><span class=\"token punctuation\">(<\/span>row<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> count <span class=\"token operator\">&gt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">:<\/span><br \/>\n                df<span class=\"token punctuation\">[<\/span>j<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#043;&#061;<\/span> <span class=\"token number\">1<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> df<\/p>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">inverse_document_frequency<\/span><span class=\"token punctuation\">(<\/span>df<span class=\"token punctuation\">,<\/span> n_docs<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token punctuation\">[<\/span>math<span class=\"token punctuation\">.<\/span>log<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>n_docs <span class=\"token operator\">&#043;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">\/<\/span> <span class=\"token punctuation\">(<\/span>d <span class=\"token operator\">&#043;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#043;<\/span> <span class=\"token number\">1<\/span> <span class=\"token keyword\">for<\/span> d <span class=\"token keyword\">in<\/span> df<span class=\"token punctuation\">]<\/span><\/p>\n<p>\u4e24\u4e2a\u503c\u5f97\u6307\u51fa\u7684\u5e73\u6ed1\u6280\u5de7\u3002(n&#043;1)\/(d&#043;1) \u907f\u514d log(x\/0)\u3002\u5c3e\u90e8\u7684 &#043;1 \u786e\u4fdd\u51fa\u73b0\u5728\u6bcf\u4e2a\u6587\u6863\u4e2d\u7684\u8bcd IDF \u4ecd\u4e3a 1&#xff08;\u800c\u975e 0&#xff09;&#xff0c;\u4e0e scikit-learn \u7684\u9ed8\u8ba4\u884c\u4e3a\u4e00\u81f4\u3002\u5176\u4ed6\u5b9e\u73b0\u4f7f\u7528\u539f\u59cb\u7684 log(N\/df)\u3002\u4e24\u79cd\u65b9\u5f0f\u90fd\u53ef\u4ee5&#xff1b;\u5e73\u6ed1\u7248\u672c\u66f4\u53cb\u597d\u3002<\/p>\n<h4>\u6b65\u9aa4 4&#xff1a;TF-IDF<\/h4>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">tfidf<\/span><span class=\"token punctuation\">(<\/span>bow_matrix<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    n_docs <span class=\"token operator\">&#061;<\/span> <span class=\"token builtin\">len<\/span><span class=\"token punctuation\">(<\/span>bow_matrix<span class=\"token punctuation\">)<\/span><br \/>\n    df <span class=\"token operator\">&#061;<\/span> document_frequency<span class=\"token punctuation\">(<\/span>bow_matrix<span class=\"token punctuation\">)<\/span><br \/>\n    idf <span class=\"token operator\">&#061;<\/span> inverse_document_frequency<span class=\"token punctuation\">(<\/span>df<span class=\"token punctuation\">,<\/span> n_docs<span class=\"token punctuation\">)<\/span><br \/>\n    out <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> row <span class=\"token keyword\">in<\/span> bow_matrix<span class=\"token punctuation\">:<\/span><br \/>\n        length <span class=\"token operator\">&#061;<\/span> <span class=\"token builtin\">sum<\/span><span class=\"token punctuation\">(<\/span>row<span class=\"token punctuation\">)<\/span><br \/>\n        tf <span class=\"token operator\">&#061;<\/span> term_frequency<span class=\"token punctuation\">(<\/span>row<span class=\"token punctuation\">,<\/span> length<span class=\"token punctuation\">)<\/span><br \/>\n        out<span class=\"token punctuation\">.<\/span>append<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">[<\/span>tf_j <span class=\"token operator\">*<\/span> idf_j <span class=\"token keyword\">for<\/span> tf_j<span class=\"token punctuation\">,<\/span> idf_j <span class=\"token keyword\">in<\/span> <span class=\"token builtin\">zip<\/span><span class=\"token punctuation\">(<\/span>tf<span class=\"token punctuation\">,<\/span> idf<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> out<\/p>\n<p><span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> docs <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><br \/>\n<span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span>     <span class=\"token punctuation\">[<\/span><span class=\"token string\">&#034;the&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;cat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;sat&#034;<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span><br \/>\n<span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span>     <span class=\"token punctuation\">[<\/span><span class=\"token string\">&#034;the&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;dog&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;sat&#034;<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span><br \/>\n<span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span>     <span class=\"token punctuation\">[<\/span><span class=\"token string\">&#034;the&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;cat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;ran&#034;<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span><br \/>\n<span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span><span class=\"token punctuation\">.<\/span> <span class=\"token punctuation\">]<\/span><br \/>\n<span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> vocab <span class=\"token operator\">&#061;<\/span> build_vocab<span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> bow <span class=\"token operator\">&#061;<\/span> bag_of_words<span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">,<\/span> vocab<span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token operator\">&gt;&gt;<\/span><span class=\"token operator\">&gt;<\/span> tfidf<span class=\"token punctuation\">(<\/span>bow<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u4e09\u4e2a\u6587\u6863&#xff0c;\u4e94\u4e2a\u8bcd\u6c47\u8bcd&#xff08;the\u3001cat\u3001sat\u3001dog\u3001ran&#xff09;\u3002the \u51fa\u73b0\u5728\u5168\u90e8\u4e09\u4e2a\u6587\u6863\u4e2d&#xff0c;\u6240\u4ee5 IDF \u4f4e\u3002dog \u53ea\u51fa\u73b0\u5728\u4e00\u4e2a\u6587\u6863\u4e2d&#xff0c;\u6240\u4ee5 IDF \u9ad8\u3002\u5411\u91cf\u662f\u7a00\u758f\u7684&#xff08;\u5927\u591a\u6570\u6761\u76ee\u5f88\u5c0f&#xff09;&#xff0c;\u533a\u5206\u6027\u5f3a\u7684\u8bcd\u51f8\u663e\u51fa\u6765\u3002<\/p>\n<h4>\u6b65\u9aa4 5&#xff1a;L2 \u5f52\u4e00\u5316<\/h4>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">l2_normalize<\/span><span class=\"token punctuation\">(<\/span>matrix<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    out <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> row <span class=\"token keyword\">in<\/span> matrix<span class=\"token punctuation\">:<\/span><br \/>\n        norm <span class=\"token operator\">&#061;<\/span> math<span class=\"token punctuation\">.<\/span>sqrt<span class=\"token punctuation\">(<\/span><span class=\"token builtin\">sum<\/span><span class=\"token punctuation\">(<\/span>x <span class=\"token operator\">*<\/span> x <span class=\"token keyword\">for<\/span> x <span class=\"token keyword\">in<\/span> row<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><br \/>\n        out<span class=\"token punctuation\">.<\/span>append<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">[<\/span>x <span class=\"token operator\">\/<\/span> norm <span class=\"token keyword\">if<\/span> norm <span class=\"token keyword\">else<\/span> <span class=\"token number\">0<\/span> <span class=\"token keyword\">for<\/span> x <span class=\"token keyword\">in<\/span> row<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> out<\/p>\n<p>\u6ca1\u6709\u5f52\u4e00\u5316&#xff0c;\u8f83\u957f\u7684\u6587\u6863\u4f1a\u5f97\u5230\u66f4\u5927\u7684\u5411\u91cf&#xff0c;\u5728\u76f8\u4f3c\u5ea6\u8ba1\u7b97\u4e2d\u5360\u4e3b\u5bfc\u3002L2 \u5f52\u4e00\u5316\u5c06\u6bcf\u4e2a\u6587\u6863\u6620\u5c04\u5230\u5355\u4f4d\u8d85\u7403\u9762\u4e0a\u3002\u884c\u4e4b\u95f4\u7684\u4f59\u5f26\u76f8\u4f3c\u5ea6\u73b0\u5728\u5c31\u662f\u70b9\u79ef\u3002<\/p>\n<h3>\u5b9e\u9645\u5e94\u7528<\/h3>\n<p>scikit-learn \u63d0\u4f9b\u4e86\u751f\u4ea7\u7ea7\u7248\u672c\u3002<\/p>\n<p><span class=\"token keyword\">from<\/span> sklearn<span class=\"token punctuation\">.<\/span>feature_extraction<span class=\"token punctuation\">.<\/span>text <span class=\"token keyword\">import<\/span> CountVectorizer<span class=\"token punctuation\">,<\/span> TfidfVectorizer<\/p>\n<p>docs <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token string\">&#034;the cat sat on the mat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;the dog sat on the mat&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;the cat ran&#034;<\/span><span class=\"token punctuation\">]<\/span><\/p>\n<p>bow_vectorizer <span class=\"token operator\">&#061;<\/span> CountVectorizer<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><br \/>\nbow <span class=\"token operator\">&#061;<\/span> bow_vectorizer<span class=\"token punctuation\">.<\/span>fit_transform<span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token keyword\">print<\/span><span class=\"token punctuation\">(<\/span>bow_vectorizer<span class=\"token punctuation\">.<\/span>get_feature_names_out<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token keyword\">print<\/span><span class=\"token punctuation\">(<\/span>bow<span class=\"token punctuation\">.<\/span>toarray<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><\/p>\n<p>tfidf_vectorizer <span class=\"token operator\">&#061;<\/span> TfidfVectorizer<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><br \/>\ntfidf <span class=\"token operator\">&#061;<\/span> tfidf_vectorizer<span class=\"token punctuation\">.<\/span>fit_transform<span class=\"token punctuation\">(<\/span>docs<span class=\"token punctuation\">)<\/span><br \/>\n<span class=\"token keyword\">print<\/span><span class=\"token punctuation\">(<\/span>tfidf<span class=\"token punctuation\">.<\/span>toarray<span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">.<\/span><span class=\"token builtin\">round<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">3<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><\/p>\n<p>CountVectorizer \u4e00\u6b21\u8c03\u7528\u5b8c\u6210\u5206\u8bcd\u3001\u8bcd\u6c47\u6784\u5efa\u548c BoW\u3002TfidfVectorizer \u5728\u6b64\u57fa\u7840\u4e0a\u52a0\u5165 IDF \u52a0\u6743\u548c L2 \u5f52\u4e00\u5316\u3002\u4e24\u8005\u90fd\u8fd4\u56de\u7a00\u758f\u77e9\u9635\u3002\u5bf9\u4e8e 10 \u4e07\u6587\u6863&#xff0c;\u5bc6\u96c6\u7248\u672c\u65e0\u6cd5\u653e\u5165\u5185\u5b58&#xff1b;\u4fdd\u6301\u7a00\u758f\u76f4\u5230\u5206\u7c7b\u5668\u8981\u6c42\u5bc6\u96c6\u683c\u5f0f\u3002<\/p>\n<p>\u6539\u53d8\u4e00\u5207\u7684\u5173\u952e\u53c2\u6570&#xff1a;<\/p>\n<table>\n<tr>\u53c2\u6570\u6548\u679c<\/tr>\n<tbody>\n<tr>\n<td>ngram_range&#061;(1, 2)<\/td>\n<td>\u5305\u542b bigram\u3002\u901a\u5e38\u63d0\u5347\u5206\u7c7b\u6548\u679c\u3002<\/td>\n<\/tr>\n<tr>\n<td>min_df&#061;2<\/td>\n<td>\u4e22\u5f03\u51fa\u73b0\u5728\u5c11\u4e8e 2 \u4e2a\u6587\u6863\u4e2d\u7684\u8bcd\u3002\u5728\u566a\u58f0\u6570\u636e\u4e0a\u7f29\u51cf\u8bcd\u6c47\u8868\u3002<\/td>\n<\/tr>\n<tr>\n<td>max_df&#061;0.95<\/td>\n<td>\u4e22\u5f03\u51fa\u73b0\u5728\u8d85\u8fc7 95% \u6587\u6863\u4e2d\u7684\u8bcd\u3002\u65e0\u9700\u786c\u7f16\u7801\u5217\u8868\u5373\u53ef\u8fd1\u4f3c\u79fb\u9664\u505c\u7528\u8bcd\u3002<\/td>\n<\/tr>\n<tr>\n<td>stop_words&#061;&#034;english&#034;<\/td>\n<td>scikit-learn \u5185\u7f6e\u505c\u7528\u8bcd\u8868\u3002\u53d6\u51b3\u4e8e\u4efb\u52a1\u2014\u2014\u60c5\u611f\u5206\u6790\u4e0d\u5e94\u4e22\u5f03\u5426\u5b9a\u8bcd\u3002<\/td>\n<\/tr>\n<tr>\n<td>sublinear_tf&#061;True<\/td>\n<td>\u4f7f\u7528 1 &#043; log(tf) \u4ee3\u66ff\u539f\u59cb tf\u3002\u5f53\u4e00\u4e2a\u8bcd\u5728\u67d0\u4e2a\u6587\u6863\u4e2d\u91cd\u590d\u591a\u6b21\u65f6\u6709\u5e2e\u52a9\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4>TF-IDF \u4ecd\u7136\u80dc\u51fa\u7684\u573a\u666f&#xff08;\u622a\u81f3 2026 \u5e74&#xff09;<\/h4>\n<ul>\n<li>\u5783\u573e\u90ae\u4ef6\u68c0\u6d4b\u3001\u4e3b\u9898\u6807\u6ce8\u3001\u65e5\u5fd7\u5f02\u5e38\u6807\u8bb0\u3002\u8bcd\u7684\u51fa\u73b0\u662f\u5173\u952e&#xff1b;\u8bed\u4e49\u7ec6\u5fae\u5dee\u522b\u4e0d\u91cd\u8981\u3002<\/li>\n<li>\u4f4e\u6570\u636e\u573a\u666f&#xff08;\u6570\u767e\u4e2a\u6807\u6ce8\u6837\u672c&#xff09;\u3002TF-IDF \u52a0\u903b\u8f91\u56de\u5f52\u6ca1\u6709\u9884\u8bad\u7ec3\u6210\u672c\u3002<\/li>\n<li>\u4efb\u4f55\u5ef6\u8fdf\u654f\u611f\u7684\u573a\u666f\u3002TF-IDF \u52a0\u7ebf\u6027\u6a21\u578b\u5728\u5fae\u79d2\u7ea7\u54cd\u5e94\u3002\u901a\u8fc7 Transformer \u5d4c\u5165\u6587\u6863\u9700\u8981 10-100ms\u3002<\/li>\n<li>\u9700\u8981\u89e3\u91ca\u9884\u6d4b\u7ed3\u679c\u7684\u7cfb\u7edf\u3002\u68c0\u67e5\u5206\u7c7b\u5668\u7cfb\u6570&#xff0c;\u6392\u540d\u9760\u524d\u7684\u6b63\u5411\u8bcd\u5c31\u662f\u539f\u56e0\u3002<\/li>\n<\/ul>\n<h4>TF-IDF \u5931\u8d25\u7684\u573a\u666f<\/h4>\n<p>\u8bed\u4e49\u76f2\u533a\u5931\u8d25\u3002\u770b\u8fd9\u4e24\u4e2a\u6587\u6863&#xff1a;<\/p>\n<ul>\n<li>\u201cThe movie was not good at all.\u201d<\/li>\n<li>\u201cThe movie was excellent.\u201d<\/li>\n<\/ul>\n<p>\u4e00\u6761\u662f\u8d1f\u9762\u8bc4\u4ef7&#xff0c;\u4e00\u6761\u662f\u6b63\u9762\u8bc4\u4ef7\u3002\u5b83\u4eec\u7684 TF-IDF \u91cd\u53e0\u90e8\u5206\u53ea\u6709 {the, movie, was}\u3002\u8bcd\u888b\u5206\u7c7b\u5668\u5fc5\u987b\u8bb0\u4f4f not \u51fa\u73b0\u5728 good \u9644\u8fd1\u4f1a\u7ffb\u8f6c\u6807\u7b7e\u3002\u5728\u8db3\u591f\u591a\u7684\u6570\u636e\u4e0a\u5b83\u53ef\u4ee5\u5b66\u5230&#xff0c;\u4f46\u6c38\u8fdc\u4e0d\u5982\u7406\u89e3\u53e5\u6cd5\u7684\u6a21\u578b\u6765\u5f97\u4f18\u96c5\u3002<\/p>\n<p>\u53e6\u4e00\u4e2a\u5931\u8d25&#xff1a;\u63a8\u7406\u65f6\u7684\u8bcd\u6c47\u5916 (out-of-vocabulary) \u8bcd\u3002\u5728 IMDb \u8bc4\u8bba\u4e0a\u8bad\u7ec3\u7684 BoW \u6a21\u578b\u5bf9 Zoomer-approved \u8fd9\u79cd\u8bad\u7ec3\u4e2d\u4ece\u672a\u51fa\u73b0\u7684 token \u5b8c\u5168\u65e0\u80fd\u4e3a\u529b\u3002\u5b50\u8bcd\u5d4c\u5165&#xff08;\u7b2c 04 \u8bfe&#xff09;\u53ef\u4ee5\u5904\u7406\u8fd9\u4e2a\u95ee\u9898\u3002TF-IDF \u4e0d\u884c\u3002<\/p>\n<h4>\u6df7\u5408\u65b9\u6848&#xff1a;TF-IDF \u52a0\u6743\u5d4c\u5165<\/h4>\n<p>2026 \u5e74\u4e2d\u7b49\u6570\u636e\u91cf\u5206\u7c7b\u7684\u5b9e\u7528\u9ed8\u8ba4\u65b9\u6848&#xff1a;\u5c06 TF-IDF \u6743\u91cd\u4f5c\u4e3a\u8bcd\u5d4c\u5165\u4e0a\u7684\u6ce8\u610f\u529b\u6743\u91cd\u3002<\/p>\n<p><span class=\"token keyword\">def<\/span> <span class=\"token function\">tfidf_weighted_embedding<\/span><span class=\"token punctuation\">(<\/span>doc<span class=\"token punctuation\">,<\/span> tfidf_scores<span class=\"token punctuation\">,<\/span> embedding_table<span class=\"token punctuation\">,<\/span> dim<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n    vec <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">[<\/span><span class=\"token number\">0.0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">*<\/span> dim<br \/>\n    total_weight <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0.0<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> token <span class=\"token keyword\">in<\/span> doc<span class=\"token punctuation\">:<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> token <span class=\"token keyword\">not<\/span> <span class=\"token keyword\">in<\/span> embedding_table <span class=\"token keyword\">or<\/span> token <span class=\"token keyword\">not<\/span> <span class=\"token keyword\">in<\/span> tfidf_scores<span class=\"token punctuation\">:<\/span><br \/>\n            <span class=\"token keyword\">continue<\/span><br \/>\n        weight <span class=\"token operator\">&#061;<\/span> tfidf_scores<span class=\"token punctuation\">[<\/span>token<span class=\"token punctuation\">]<\/span><br \/>\n        emb <span class=\"token operator\">&#061;<\/span> embedding_table<span class=\"token punctuation\">[<\/span>token<span class=\"token punctuation\">]<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> i <span class=\"token keyword\">in<\/span> <span class=\"token builtin\">range<\/span><span class=\"token punctuation\">(<\/span>dim<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">:<\/span><br \/>\n            vec<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#043;&#061;<\/span> weight <span class=\"token operator\">*<\/span> emb<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span><br \/>\n        total_weight <span class=\"token operator\">&#043;&#061;<\/span> weight<br \/>\n    <span class=\"token keyword\">if<\/span> total_weight <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">:<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> vec<br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token punctuation\">[<\/span>v <span class=\"token operator\">\/<\/span> total_weight <span class=\"token keyword\">for<\/span> v <span class=\"token keyword\">in<\/span> vec<span class=\"token punctuation\">]<\/span><\/p>\n<p>\u4f60\u4ece\u5d4c\u5165\u83b7\u5f97\u8bed\u4e49\u80fd\u529b&#xff0c;\u4ece TF-IDF \u83b7\u5f97\u7a00\u6709\u8bcd\u7684\u5f3a\u8c03\u3002\u5206\u7c7b\u5668\u5728\u6c60\u5316\u540e\u7684\u5411\u91cf\u4e0a\u8bad\u7ec3\u3002\u5728\u5927\u7ea6 5 \u4e07\u4e2a\u6807\u6ce8\u6837\u672c\u4ee5\u4e0b\u7684\u60c5\u611f\u5206\u6790\u3001\u4e3b\u9898\u5206\u7c7b\u548c\u610f\u56fe\u5206\u7c7b\u4efb\u52a1\u4e0a&#xff0c;\u8fd9\u79cd\u65b9\u6848\u4f18\u4e8e\u5355\u72ec\u4f7f\u7528\u4efb\u4e00\u65b9\u6cd5\u3002<\/p>\n<h3>\u4ea4\u4ed8<\/h3>\n<p>\u4fdd\u5b58\u4e3a outputs\/prompt-vectorization-picker.md&#xff1a;<\/p>\n<p>&#8212;<br \/>\nname: vectorization-picker<br \/>\ndescription: Given a text-classification task, recommend BoW, TF-IDF, embeddings, or a hybrid.<br \/>\nphase: 5<br \/>\nlesson: 02<br \/>\n&#8212;<\/p>\n<p>You recommend a text-vectorization strategy. Given a task description, output:<\/p>\n<p>1. Representation (BoW, TF-IDF, transformer embeddings, or a hybrid). Explain why in one sentence.<br \/>\n2. Specific vectorizer configuration. Name the library. Quote the arguments (&#096;ngram_range&#096;, &#096;min_df&#096;, &#096;max_df&#096;, &#096;sublinear_tf&#096;, &#096;stop_words&#096;).<br \/>\n3. One failure mode to test before shipping.<\/p>\n<p>Refuse to recommend embeddings when the user has under 500 labeled examples unless they show evidence of semantic failure in a TF-IDF baseline. Refuse to remove stopwords for sentiment analysis (negations carry signal). Flag class imbalance as needing more than a vectorizer change.<\/p>\n<p>Example input: &#034;Classifying 30k customer support tickets into 12 categories. Most tickets are 2-3 sentences. English only. Need explainability for audit logs.&#034;<\/p>\n<p>Example output:<\/p>\n<p>&#8211; Representation: TF-IDF. 30k examples is not small; explainability requirement rules out dense embeddings.<br \/>\n&#8211; Config: &#096;TfidfVectorizer(ngram_range&#061;(1, 2), min_df&#061;3, max_df&#061;0.95, sublinear_tf&#061;True, stop_words&#061;None)&#096;. Keep stopwords because category keywords sometimes are stopwords (&#034;not working&#034; vs &#034;working&#034;).<br \/>\n&#8211; Failure to test: verify &#096;min_df&#061;3&#096; does not drop rare category keywords. Run &#096;get_feature_names_out&#096; filtered by class and eyeball.<\/p>\n<h3>\u7ec3\u4e60<\/h3>\n<li>\u7b80\u5355\u3002 \u5728 L2 \u5f52\u4e00\u5316\u7684 TF-IDF \u8f93\u51fa\u4e0a\u5b9e\u73b0 cosine_similarity(doc_vec_a, doc_vec_b)\u3002\u9a8c\u8bc1\u76f8\u540c\u6587\u6863\u7684\u5f97\u5206\u4e3a 1.0&#xff0c;\u8bcd\u6c47\u5b8c\u5168\u4e0d\u91cd\u53e0\u7684\u6587\u6863\u5f97\u5206\u4e3a 0.0\u3002<\/li>\n<li>\u4e2d\u7b49\u3002 \u4e3a bag_of_words \u6dfb\u52a0 n-gram \u652f\u6301\u3002\u53c2\u6570 n \u751f\u6210 n-gram \u7684\u8ba1\u6570\u3002\u6d4b\u8bd5 n&#061;2 \u5728 [&#034;the&#034;, &#034;cat&#034;, &#034;sat&#034;] \u4e0a\u4ea7\u751f bigram \u8ba1\u6570 [&#034;the cat&#034;, &#034;cat sat&#034;]\u3002<\/li>\n<li>\u56f0\u96be\u3002 \u4f7f\u7528 GloVe 100d \u5411\u91cf\u6784\u5efa\u4e0a\u8ff0 TF-IDF \u52a0\u6743\u5d4c\u5165\u6df7\u5408\u65b9\u6848&#xff08;\u4e0b\u8f7d\u4e00\u6b21\u5e76\u7f13\u5b58&#xff09;\u3002\u5728 20 Newsgroups \u6570\u636e\u96c6\u4e0a\u5bf9\u6bd4\u7eaf TF-IDF \u548c\u7eaf\u5e73\u5747\u6c60\u5316\u5d4c\u5165\u7684\u5206\u7c7b\u51c6\u786e\u7387\u3002\u62a5\u544a\u54ea\u79cd\u65b9\u6cd5\u5728\u4f55\u5904\u80dc\u51fa\u3002<\/li>\n<h3>\u5173\u952e\u672f\u8bed<\/h3>\n<table>\n<tr>\u672f\u8bed\u4eba\u4eec\u7684\u8bf4\u6cd5\u5b9e\u9645\u542b\u4e49<\/tr>\n<tbody>\n<tr>\n<td>BoW<\/td>\n<td>\u8bcd\u9891\u5411\u91cf<\/td>\n<td>\u4e00\u4e2a\u6587\u6863\u4e2d\u8bcd\u6c47\u8868\u8bcd\u7684\u8ba1\u6570\u3002\u4e22\u5f03\u4e86\u8bcd\u5e8f\u3002<\/td>\n<\/tr>\n<tr>\n<td>TF<\/td>\n<td>\u8bcd\u9891<\/td>\n<td>\u4e00\u4e2a\u8bcd\u5728\u6587\u6863\u4e2d\u7684\u51fa\u73b0\u6b21\u6570&#xff0c;\u53ef\u9009\u62e9\u6309\u6587\u6863\u957f\u5ea6\u5f52\u4e00\u5316\u3002<\/td>\n<\/tr>\n<tr>\n<td>DF<\/td>\n<td>\u6587\u6863\u9891\u7387<\/td>\n<td>\u81f3\u5c11\u5305\u542b\u8be5\u8bcd\u4e00\u6b21\u7684\u6587\u6863\u6570\u91cf\u3002<\/td>\n<\/tr>\n<tr>\n<td>IDF<\/td>\n<td>\u9006\u6587\u6863\u9891\u7387<\/td>\n<td>\u7ecf\u5e73\u6ed1\u7684 log(N \/ df)\u3002\u964d\u4f4e\u51fa\u73b0\u5728\u6240\u6709\u5730\u65b9\u7684\u8bcd\u7684\u6743\u91cd\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u7a00\u758f\u5411\u91cf<\/td>\n<td>\u5927\u90e8\u5206\u4e3a\u96f6<\/td>\n<td>\u8bcd\u6c47\u8868\u901a\u5e38\u6709 1 \u4e07\u5230 10 \u4e07\u4e2a\u8bcd&#xff1b;\u5927\u591a\u6570\u5728\u7ed9\u5b9a\u6587\u6863\u4e2d\u4e0d\u51fa\u73b0\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u4f59\u5f26\u76f8\u4f3c\u5ea6<\/td>\n<td>\u5411\u91cf\u5939\u89d2<\/td>\n<td>L2 \u5f52\u4e00\u5316\u5411\u91cf\u7684\u70b9\u79ef\u30021 \u8868\u793a\u76f8\u540c&#xff0c;0 \u8868\u793a\u6b63\u4ea4\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>\u8bcd\u888b\u6a21\u578b\u3001TF-IDF \u4e0e\u6587\u672c\u8868\u793a\u5148\u8ba1\u6570&#xff0c;\u540e\u601d\u8003\u3002TF-IDF \u5728\u5b9a\u4e49\u660e\u786e\u7684\u4efb\u52a1\u4e0a\u4f9d\u7136\u80dc\u8fc7\u5d4c\u5165\u6a21\u578b&#xff0c;\u5373\u4fbf\u5728 2026 \u5e74\u3002\u7c7b\u578b&#xff1a; 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