{"id":7882,"date":"2022-09-10T19:19:35","date_gmt":"2022-09-10T13:49:35","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-nullpointer-exception-while-using-weka-classifier\/"},"modified":"2022-09-10T19:19:35","modified_gmt":"2022-09-10T13:49:35","slug":"solved-nullpointer-exception-while-using-weka-classifier","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-nullpointer-exception-while-using-weka-classifier\/","title":{"rendered":"[Solved] Nullpointer exception while using Weka classifier"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-24164345\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"24164345\" data-parentid=\"24148715\" data-score=\"0\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>Since you didn&#8217;t provide all relevant information, I&#8217;ll take a shot in the dark:<\/p>\n<p>I&#8217;m assuming that you&#8217;re using Weka version 3.7.5 and I found the following <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/grepcode.com\/file\/repo1.maven.org\/maven2\/nz.ac.waikato.cms.weka\/weka-dev\/3.7.5\/weka\/classifiers\/functions\/Logistic.java\">source code for <code>Logistic.java<\/code><\/a> online<\/p>\n<pre><code>public double [] distributionForInstance(Instance instance) throws Exception {\n    \/\/ line 710\n    m_ReplaceMissingValues.input(instance);\n    instance = m_ReplaceMissingValues.output();\n    ...\n}\n<\/code><\/pre>\n<p>Assuming you didn&#8217;t pass <code>null<\/code> for <code>instance<\/code>, this only leaves <code>m_ReplaceMissingValues<\/code>. That member is initialized when the method <code>Logistic.buildClassifier(Instances train)<\/code>is called:<\/p>\n<pre><code>public void buildClassifier(Instances train) throws Exception {\n    ...\n    \/\/ missing values   \n    m_ReplaceMissingValues = new ReplaceMissingValues();\n    m_ReplaceMissingValues.setInputFormat(train);\n    train = Filter.useFilter(train, m_ReplaceMissingValues);\n    ...\n}\n<\/code><\/pre>\n<p>It looks like you&#8217;ve never trained your classifier <code>Logistic<\/code> on any data after you created the object in the line<\/p>\n<pre><code>Classifier cls = (Classifier) Utils.forName(Classifier.class, classname, tmpOptions);\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">1<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Nullpointer exception while using Weka classifier <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] Since you didn&#8217;t provide all relevant information, I&#8217;ll take a shot in the dark: I&#8217;m assuming that you&#8217;re using Weka version 3.7.5 and I found the following source code for Logistic.java online public double [] distributionForInstance(Instance instance) throws Exception { \/\/ line 710 m_ReplaceMissingValues.input(instance); instance = m_ReplaceMissingValues.output(); &#8230; } Assuming you didn&#8217;t pass null &#8230; <a title=\"[Solved] Nullpointer exception while using Weka classifier\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-nullpointer-exception-while-using-weka-classifier\/\" aria-label=\"More on [Solved] Nullpointer exception while using Weka classifier\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[323,2214],"class_list":["post-7882","post","type-post","status-publish","format-standard","hentry","category-solved","tag-java","tag-weka"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Nullpointer exception while using Weka classifier - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-nullpointer-exception-while-using-weka-classifier\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Nullpointer exception while using Weka classifier - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] Since you didn&#8217;t provide all relevant information, I&#8217;ll take a shot in the dark: I&#8217;m assuming that you&#8217;re using Weka version 3.7.5 and I found the following source code for Logistic.java online public double [] distributionForInstance(Instance instance) throws Exception { \/\/ line 710 m_ReplaceMissingValues.input(instance); instance = m_ReplaceMissingValues.output(); ... } Assuming you didn&#8217;t pass null ... 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JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-nullpointer-exception-while-using-weka-classifier\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] Nullpointer exception while using Weka classifier - JassWeb","og_description":"[ad_1] Since you didn&#8217;t provide all relevant information, I&#8217;ll take a shot in the dark: I&#8217;m assuming that you&#8217;re using Weka version 3.7.5 and I found the following source code for Logistic.java online public double [] distributionForInstance(Instance instance) throws Exception { \/\/ line 710 m_ReplaceMissingValues.input(instance); instance = m_ReplaceMissingValues.output(); ... } Assuming you didn&#8217;t pass null ... 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