{"id":205172,"date":"2025-05-29T11:33:23","date_gmt":"2025-05-29T03:33:23","guid":{"rendered":"https:\/\/server.hk\/cnblog\/205172\/"},"modified":"2025-05-29T11:33:23","modified_gmt":"2025-05-29T03:33:23","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8-pandas-%e7%bb%9f%e8%ae%a1%e5%bd%93%e5%89%8d%e8%a1%8c%e5%80%bc%e4%b9%8b%e5%89%8d%e6%af%94%e8%af%a5%e5%80%bc%e5%a4%a7%e7%9a%84%e6%95%b0%e6%8d%ae%e7%9a%84%e4%b8%aa","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/205172\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528 Pandas \u7edf\u8ba1\u5f53\u524d\u884c\u503c\u4e4b\u524d\u6bd4\u8be5\u503c\u5927\u7684\u6570\u636e\u7684\u4e2a\u6570\uff1f"},"content":{"rendered":"<p><b><\/b>     <\/p>\n<h1>\u5982\u4f55\u4f7f\u7528 Pandas \u7edf\u8ba1\u5f53\u524d\u884c\u503c\u4e4b\u524d\u6bd4\u8be5\u503c\u5927\u7684\u6570\u636e\u7684\u4e2a\u6570\uff1f<\/h1>\n<p>\u6765\u5230\u7684\u5927\u5bb6\uff0c\u76f8\u4fe1\u90fd\u662f\u7f16\u7a0b\u5b66\u4e60\u7231\u597d\u8005\uff0c\u5e0c\u671b\u5728\u8fd9\u91cc\u5b66\u4e60\u6587\u7ae0\u76f8\u5173\u7f16\u7a0b\u77e5\u8bc6\u3002\u4e0b\u9762\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u5e26\u5927\u5bb6\u804a\u804a\u300a\u5982\u4f55\u4f7f\u7528 Pandas \u7edf\u8ba1\u5f53\u524d\u884c\u503c\u4e4b\u524d\u6bd4\u8be5\u503c\u5927\u7684\u6570\u636e\u7684\u4e2a\u6570\uff1f\u300b\uff0c\u4ecb\u7ecd\u4e00\u4e0b\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u7684\u77e5\u8bc6\u79ef\u7d2f\u6709\u6240\u5e2e\u52a9\uff0c\u52a9\u529b\u5b9e\u6218\u5f00\u53d1\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241125\/17325113756744068fe6c1e.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u5982\u4f55\u4f7f\u7528 pandas \u83b7\u53d6\u6bd4\u5f53\u524d\u884c\u503c\u5927\u7684\u6570\u636e\u7684\u8ba1\u6570<\/strong><\/p>\n<p>\u8981\u83b7\u53d6\u6bd4\u5f53\u524d\u884c\u503c\u5927\u7684\u6570\u636e\u7684\u8ba1\u6570\uff0c\u53ef\u4ee5\u4f7f\u7528 pandas \u63d0\u4f9b\u7684\u77e9\u9635\u8ba1\u7b97\u3002\u8fd9\u79cd\u65b9\u6cd5\u53ef\u4ee5\u907f\u514d\u67e5\u627e\u5faa\u73af\uff0c\u4ece\u800c\u5c06\u65f6\u95f4\u590d\u6742\u5ea6\u964d\u4f4e\u5230 <strong>o(1)<\/strong>\u3002<\/p>\n<p>\u4ee3\u7801\u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n<pre>count_larger = lambda x: np.sum(x &gt; x[-1])\ndf['col4'] = [count_larger(df[:i + 1]['col3'].values) for i in range(len(df))]<\/pre>\n<p><strong>\u4ee3\u7801\u8bf4\u660e\uff1a<\/strong><\/p>\n<ul>\n<li>count_larger \u51fd\u6570\u662f\u4e00\u4e2a lambda \u8868\u8fbe\u5f0f\uff0c\u5b83\u8ba1\u7b97\u4e00\u4e2a\u6570\u7ec4\u4e2d\u5927\u4e8e\u5176\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u7684\u503c\u7684\u6570\u91cf\u3002<\/li>\n<li>df[:i + 1][&#8216;col3&#8217;].values \u83b7\u53d6\u4ece\u7b2c 0 \u884c\u5230\u7b2c i \u884c\u7684 &#8216;col3&#8217; \u5217\u7684\u503c\uff0c\u5e76\u5c06\u5176\u8f6c\u6362\u4e3a numpy \u6570\u7ec4\u3002<\/li>\n<li>\u5bf9\u4e8e\u6bcf\u4e00\u884c\uff0ccount_larger \u51fd\u6570\u8ba1\u7b97\u6bd4\u8be5\u884c &#8216;col3&#8217; \u503c\u5927\u7684\u503c\u7684\u8ba1\u6570\u3002<\/li>\n<li>[count_larger(df[:i + 1][&#8216;col3&#8217;].values) for i in range(len(df))] \u4f7f\u7528\u5217\u8868\u63a8\u5bfc\u4e3a\u6bcf\u4e00\u884c\u8ba1\u7b97\u8ba1\u6570\uff0c\u5e76\u5c06\u5176\u4f5c\u4e3a &#8216;col4&#8217; \u5217\u6dfb\u52a0\u5230 dataframe \u4e2d\u3002<\/li>\n<\/ul>\n<p>\u6700\u7ec8\uff0c\u4f60\u4f1a\u5f97\u5230\u4e00\u4e2a\u65b0\u7684 &#8216;col4&#8217; 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