{"id":186,"date":"2020-09-24T08:33:11","date_gmt":"2020-09-24T00:33:11","guid":{"rendered":"http:\/\/www.gaoxigang.com\/?p=186"},"modified":"2020-09-24T08:33:11","modified_gmt":"2020-09-24T00:33:11","slug":"python-%e6%9c%ba%e5%99%a8%e5%ad%a6%e4%b9%a0-k%e8%bf%91%e9%82%bb%e8%af%86%e5%88%ab%e5%9b%be%e5%bd%a2%e5%9b%be%e5%83%8f","status":"publish","type":"post","link":"https:\/\/www.gaoxigang.com\/index.php\/2020\/09\/24\/python-%e6%9c%ba%e5%99%a8%e5%ad%a6%e4%b9%a0-k%e8%bf%91%e9%82%bb%e8%af%86%e5%88%ab%e5%9b%be%e5%bd%a2%e5%9b%be%e5%83%8f\/","title":{"rendered":"Python \u673a\u5668\u5b66\u4e60-K\u8fd1\u90bb\u8bc6\u522b\u56fe\u5f62\u56fe\u50cf"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">K\u8fd1\u90bb\u8bc6\u522b\u56fe\u7247<\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u5728\u672c\u7bc7\u6587\u7ae0\u4e2d\u6211\u4eec\u4f7f\u7528sklearn\u4e2d\u81ea\u5e26\u7684\u624b\u5199\u6570\u5b57\u6570\u636e\u96c6\uff08digits\uff09\uff0c\u8fd9\u4e2a\u6570\u636e\u96c6\u4e2d\u5e76\u6ca1\u6709\u56fe\u7247\uff0c\u800c\u662f\u7ecf\u8fc7\u63d0\u53d6\u5f97\u5230\u7684\u624b\u5199\u6570\u5b57\u7279\u5f81\u548c\u6807\u8bb0\uff0c\u5c31\u514d\u53bb\u4e86\u6211\u4eec\u7684\u63d0\u53d6\u6570\u636e\u7684\u9ebb\u70e6\uff0c\u4f46\u662f\u5728\u5b9e\u9645\u7684\u5e94\u7528\u4e2d\u662f\u9700\u8981\u6211\u4eec\u5bf9\u56fe\u7247\u4e2d\u7684\u6570\u636e\u8fdb\u884c\u63d0\u53d6\u7684<\/p><\/blockquote>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"python\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">from sklearn.model_selection import train_test_split\nfrom sklearn.neighbors import KNeighborsClassifier\nfrom sklearn.datasets import load_digits\nimport pandas as pd\nimport matplotlib.pyplot as plt\n\n# 1: \u6570\u636e\u83b7\u53d6 scrapy\ndigits = load_digits()\n# print(digits,type(digits))\n# print(digits['DESCR'])\nX = digits['data']\ny = digits['target']\n# print(X,X.shape)\n# print(y,y.shape)\n# \u663e\u793a\u7b2c35\u5f20\u56fe\u7684\u7279\u5f81\u503c\u548c\u76ee\u6807\u503c\n# digit = X[35]\n# digit_image = digit.reshape(8,8)\n# plt.imshow(digit_image)\n# plt.show()\n# print(y[35])\nX_train, X_test, y_train, y_test = train_test_split(X,y,test_size=0.25,random_state=1)\nfrom sklearn.neighbors import KNeighborsClassifier\n# \u8d85\u53c2\u6570: \u673a\u5668\u6a21\u578b\u5728\u8bad\u7ec3\u4e4b\u524d\u5fc5\u987b\u6307\u5b9a\u7684\u53c2\u6570  n_neighbors weights\n# \u6a21\u578b\u53c2\u6570\uff1a\u7b97\u6cd5\u8bad\u7ec3\u7684\u8fc7\u7a0b\u4e2d\u5b66\u4e60\u7684\u53c2\u6570. KNN\u6ca1\u6709\u6a21\u578b\u53c2\u6570\uff0c\u53ea\u6709\u8d85\u53c2\u6570\n#  y = w * x + b ===> w,b \u5c31\u662f\u6a21\u578b\u53c2\u6570\nknn = KNeighborsClassifier(n_neighbors=20,weights=\"distance\")\n# \u6a21\u578b\u8bad\u7ec3\nknn.fit(X_train,y_train)\ny_predict = knn.predict(X_test)\nprint('\u547d\u4e2d\u7387', knn.score(X_test,y_test))\n<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">PCA\u4e3b\u6210\u5206\u5206\u6790<\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u5728\u5f88\u591a\u673a\u5668\u5b66\u4e60\u7b97\u6cd5\u7684\u590d\u6742\u5ea6\u548c\u6570\u636e\u7684\u7ef4\u5ea6\u6709\u7740\u5bc6\u5207\u7684\u5173\u7cfb\uff0c\u751a\u81f3\u4e0e\u7ef4\u6570\u5448\u73b0\u6307\u6570\u7ea7\u5173\u8054\u3002\u5728\u56fe\u5f62\u56fe\u50cf\u4e2d\u673a\u5668\u5b66\u4e60\u5904\u7406\u6210\u5343\u4e0a\u4e07\u751a\u81f3\u51e0\u5341\u4e07\u7684\u7ef4\u5ea6\u7684\u60c5\u51b5\u4e5f\u5e76\u4e0d\u7f55\u89c1\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u673a\u5668\u5b66\u4e60\u7684\u8d44\u6e90\u6d88\u8017\u662f\u4e0d\u53ef\u63a5\u6536\u7684\uff0c\u56e0\u6b64\u6211\u4eec\u5fc5\u987b\u5bf9\u6570\u636e\u8fdb\u884c\u964d\u7ef4\u5904\u7406<\/p><\/blockquote>\n\n\n\n<ol class=\"wp-block-list\"><li>\u4e3b\u8981\u7528\u4e8e\u6570\u636e\u7684\u964d\u7ef4 \u901a\u8fc7\u964d\u7ef4\uff0c\u53ef\u4ee5\u53d1\u73b0\u66f4\u4fbf\u4e8e\u4eba\u7c7b\u7406\u89e3\u7684\u7279\u5f81<\/li><li>\u5176\u5b83\u5e94\u7528\uff1a\u53ef\u89c6\u5316\uff0c\u53bb\u566a\u97f3<\/li><li>\u964d\u7ef4\u5f53\u7136\u610f\u5473\u7740\u4fe1\u606f\u7684\u4e22\u5931\uff0c\u4e0d\u8fc7\u9274\u4e8e\u5b9e\u9645\u6570\u636e\u672c\u8eab\u901a\u5e38\u5b58\u5728\u76f8\u5173\u6027\uff0c\u6211\u4eec\u53ef\u4ee5\u60f3\u529e\u6cd5\u5728\u964d\u7ef4\u7684\u540c\u65f6\u5c06\u4fe1\u606f\u7684\u635f\u5931\u5c3d\u91cf\u964d\u4f4e<\/li><\/ol>\n\n\n\n<p><strong>\u4e00\u4e9b\u76f8\u5173\u6027\u6848\u4f8b<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>\u201c\u6d4f\u89c8\u91cf&#8221;\u548c&#8221;\u8bbf\u5ba2\u6570\u201d \u5f80\u5f80\u5177\u6709\u8f83\u5f3a\u7684\u76f8\u5173\u6027<\/li><li>\u201c\u4e0b\u5355\u6570\u201d\u548c&#8221;\u6210\u4ea4\u6570&#8221; \u4e5f\u5177\u6709\u8f83\u5f3a\u7684\u76f8\u5173\u6027<\/li><li>\u201c\u5b66\u5386\u201d\u548c&#8221;\u5b66\u4f4d&#8221; \u5177\u6709\u8f83\u5f3a\u7684\u76f8\u5173\u6027<\/li><\/ol>\n\n\n\n<h2 class=\"wp-block-heading\">\u91c7\u7528PCA\u964d\u7ef4\u63d0\u793a\u8fd0\u7b97\u6548\u7387<\/h2>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"python\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">import numpy as np\nimport matplotlib.pyplot as plt\nfrom sklearn import datasets\nfrom sklearn.decomposition import PCA\nfrom sklearn.neighbors import KNeighborsClassifier\nfrom sklearn.model_selection import train_test_split\n\nplt.rcParams['font.sans-serif']=['SimHei']\n\ndigits = datasets.load_digits()\nX = digits['data']\ny = digits['target']\n# n_components=64 ==> \u6b63\u786e\u7387\u4e3a: 0.98888\n# n_components=2  \u7279\u5f81\u4fdd\u7559\u767e\u5206\u6bd4\u4e3a: 28%    \u6b63\u786e\u7387\u4e3a: 60%\n# n_components=30   \u7279\u5f81\u4fdd\u7559\u767e\u5206\u6bd4\u4e3a: 95%    \u6b63\u786e\u7387\u4e3a: 0.9933  \u601d\u8003\u4e3a\u4ec0\u4e48\u4f1a\u8d85\u8fc7n_components=64\u7684\u60c5\u51b5\npca = PCA(n_components=2) # \u76f4\u63a5\u964d\u4f4e\u523030\u7279\u5f81\u503c\nX = pca.fit_transform(X)\n# # \u5b83\u4ee3\u8868\u964d\u7ef4\u540e\u7684\u5404\u4e3b\u6210\u5206\u7684\u65b9\u5dee\u503c\u5360\u603b\u65b9\u5dee\u503c\u7684\u6bd4\u4f8b(\u4ece\u5927\u5230\u5c0f\u6392\u5e8f)\uff0c\u8fd9\u4e2a\u6bd4\u4f8b\u8d8a\u5927\uff0c\u5219\u8d8a\u662f\u91cd\u8981\u7684\u4e3b\u6210\u5206\npevr = pca.explained_variance_ratio_\nprint(f'\u6bcf\u4e2a\u7279\u5f81\u65b9\u5dee\u4e3a{pevr},\u964d\u7ef4\u540e\u7684\u7279\u5f81\u6570\u91cf\u4e3a{len(pevr)},\u4fdd\u7559\u7279\u5f81\u767e\u5206\u6bd4\u4e3a{np.sum(pevr)}')\n# # \u505a\u4e00\u4e2a\u6298\u7ebf\u56fe\uff0c\u5b8c\u6210\u5bf9\u65b9\u5dee\u503c\u7684\u4ece\u5927\u5230\u5c0f\u663e\u793a\u64cd\u4f5c\nplt.plot([i for i in range(X.shape[1])],[np.sum(pca.explained_variance_ratio_[:i+1]) for i in range(X.shape[1])])\nplt.xlabel('\u7279\u5f81\u6570\u91cf')\nplt.ylabel('\u7279\u5f81\u5b58\u7559\u767e\u5206\u6bd4')\n# \u5982\u679c\u53d6\u524d30\u4e2a\u7279\u5f81\u503c,\u4fdd\u7559\u4e4b\u524d\u5927\u7ea690%\u7684\u7ed3\u679c\nplt.show()\n\nX_train, X_test, y_train, y_test = train_test_split(X,y,random_state=1)\nprint(X_train.shape)\nknn = KNeighborsClassifier(n_neighbors=1)\nknn.fit(X_train,y_train)\ny_predict = knn.predict(X_test)\nprint(knn.score(X_test,y_test))\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>K\u8fd1\u90bb\u8bc6\u522b\u56fe\u7247 \u5728\u672c\u7bc7\u6587\u7ae0\u4e2d\u6211\u4eec\u4f7f\u7528sklearn\u4e2d\u81ea\u5e26\u7684\u624b\u5199\u6570\u5b57\u6570\u636e\u96c6\uff08digits\uff09\uff0c\u8fd9\u4e2a\u6570\u636e\u96c6\u4e2d\u5e76\u6ca1\u6709\u56fe [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-186","post","type-post","status-publish","format-standard","hentry","category-biji"],"_links":{"self":[{"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/posts\/186","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/comments?post=186"}],"version-history":[{"count":0,"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/posts\/186\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/media?parent=186"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/categories?post=186"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gaoxigang.com\/index.php\/wp-json\/wp\/v2\/tags?post=186"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}