{"id":1158,"date":"2023-07-27T11:17:42","date_gmt":"2023-07-27T11:17:42","guid":{"rendered":"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/"},"modified":"2023-07-27T11:17:42","modified_gmt":"2023-07-27T11:17:42","slug":"curva-de-rocha-ggplot2","status":"publish","type":"post","link":"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/","title":{"rendered":"Como tra\u00e7ar uma curva roc usando ggplot2 (com exemplos)"},"content":{"rendered":"<p><\/p>\n<hr>\n<p><span style=\"color: #000000;\"><a href=\"https:\/\/statorials.org\/pt\/regressao-logistica-1\/\" target=\"_blank\" rel=\"noopener noreferrer\">A regress\u00e3o log\u00edstica<\/a> \u00e9 um m\u00e9todo estat\u00edstico que usamos para ajustar um modelo de regress\u00e3o quando a vari\u00e1vel de resposta \u00e9 bin\u00e1ria. Para avaliar qu\u00e3o bem um modelo de regress\u00e3o log\u00edstica se ajusta a um conjunto de dados, podemos observar as duas m\u00e9tricas a seguir:<\/span><\/p>\n<ul>\n<li> <span style=\"color: #000000;\"><strong>Sensibilidade:<\/strong> probabilidade de o modelo prever um resultado positivo para uma observa\u00e7\u00e3o quando o resultado \u00e9 realmente positivo.<\/span><\/li>\n<li> <span style=\"color: #000000;\"><strong>Especificidade:<\/strong> a probabilidade de o modelo prever um resultado negativo para uma observa\u00e7\u00e3o quando o resultado \u00e9 realmente negativo.<\/span><\/li>\n<\/ul>\n<p> <span style=\"color: #000000;\">Uma maneira simples de visualizar essas duas m\u00e9tricas \u00e9 criar uma <strong>curva ROC<\/strong> , que \u00e9 um gr\u00e1fico que mostra a sensibilidade e a especificidade de um modelo de regress\u00e3o log\u00edstica.<\/span><\/p>\n<p> <span style=\"color: #000000;\">Este tutorial explica como criar e interpretar uma curva ROC em R usando o pacote de visualiza\u00e7\u00e3o ggplot2.<\/span><\/p>\n<h3> <strong>Exemplo: curva ROC usando ggplot2<\/strong><\/h3>\n<p> <span style=\"color: #000000;\">Suponha que ajustemos o seguinte modelo de regress\u00e3o log\u00edstica em R:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008080;\">#load <em>Default<\/em> dataset from ISLR book<\/span>\ndata &lt;- ISLR::Default\n\n<span style=\"color: #008080;\">#divide dataset into training and test set\n<\/span>set.seed(1)\nsample &lt;- sample(c( <span style=\"color: #008000;\">TRUE<\/span> , <span style=\"color: #008000;\">FALSE<\/span> ), <span style=\"color: #3366ff;\">nrow<\/span> (data), <span style=\"color: #3366ff;\">replace<\/span> = <span style=\"color: #008000;\">TRUE<\/span> , <span style=\"color: #3366ff;\">prob<\/span> =c(0.7,0.3))\ntrain &lt;- data[sample, ]\ntest &lt;- data[!sample, ]\n\n<span style=\"color: #008080;\">#fit logistic regression model to training set<\/span>\nmodel &lt;- glm(default~student+balance+income, family=\" <span style=\"color: #008000;\">binomial<\/span> \", data=train)\n\n<span style=\"color: #008080;\">#use model to make predictions on test set<\/span>\npredicted &lt;- predict(model, test, type=\" <span style=\"color: #008000;\">response<\/span> \")\n<\/strong><\/pre>\n<p> <span style=\"color: #000000;\">Para visualizar o desempenho do modelo de regress\u00e3o log\u00edstica no conjunto de teste, podemos criar um gr\u00e1fico ROC usando a fun\u00e7\u00e3o <strong>ggroc()<\/strong> do <a href=\"https:\/\/www.rdocumentation.org\/packages\/pROC\/versions\/1.16.2\/topics\/ggroc.roc\" target=\"_blank\" rel=\"noopener noreferrer\">pacote pROC<\/a> :<\/span> <\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008080;\">#load necessary packages<\/span>\n<span style=\"color: #993300;\">library<\/span> (ggplot2)\n<span style=\"color: #993300;\">library<\/span> (pROC)\n\n<span style=\"color: #008080;\">#define object to plot\n<span style=\"color: #000000;\">rocobj &lt;- roc(test$default, predicted)\n<\/span>\n#create ROC plot\n<span style=\"color: #000000;\">ggroc(rocobj)<\/span><\/span><\/strong> <\/pre>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"aligncenter wp-image-11613 \" src=\"https:\/\/statorials.org\/wp-content\/uploads\/2023\/08\/rocggplot1.png\" alt=\"Curva ROC em ggplot2\" width=\"445\" height=\"439\" srcset=\"\" sizes=\"auto, \"><\/p>\n<p> <span style=\"color: #000000;\">O eixo y exibe a sensibilidade (a taxa verdadeiramente positiva) do modelo e o eixo x exibe a especificidade (a taxa verdadeiramente negativa) do modelo.<\/span><\/p>\n<p> <span style=\"color: #000000;\">Observe que podemos adicionar estilo ao gr\u00e1fico e tamb\u00e9m fornecer um t\u00edtulo contendo a AUC (\u00e1rea sob a curva) do gr\u00e1fico:<\/span> <\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008080;\">#load necessary packages<\/span>\n<span style=\"color: #993300;\">library<\/span> (ggplot2)\n<span style=\"color: #993300;\">library<\/span> (pROC)\n\n<span style=\"color: #008080;\">#define object to plot and calculate AUC\n<\/span>rocobj &lt;- roc(test$default, predicted)\nauc &lt;- <span style=\"color: #3366ff;\">round<\/span> (auc(test$default, predicted), <span style=\"color: #3366ff;\">4<\/span> )\n\n<span style=\"color: #008080;\">#create ROC plot\n<\/span>ggroc(rocobj, color = ' <span style=\"color: #008000;\">steelblue<\/span> ', size = <span style=\"color: #008000;\">2<\/span> ) +\n  ggtitle( <span style=\"color: #3366ff;\">paste0<\/span> (' <span style=\"color: #008000;\">ROC Curve<\/span> ', ' <span style=\"color: #008000;\">(AUC =<\/span> ', auc, ' <span style=\"color: #008000;\">)<\/span> '))<\/strong> <\/pre>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"aligncenter wp-image-11614 \" src=\"https:\/\/statorials.org\/wp-content\/uploads\/2023\/08\/rocggplot2.png\" alt=\"Curva ROC com AUC em ggplot2\" width=\"452\" height=\"450\" srcset=\"\" sizes=\"auto, \"><\/p>\n<p> <span style=\"color: #000000;\">Observe que voc\u00ea tamb\u00e9m pode modificar o tema da trama:<\/span> <\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008080;\">#create ROC plot with minimal theme\n<\/span>ggroc(rocobj, color = ' <span style=\"color: #008000;\">steelblue<\/span> ', size = <span style=\"color: #008000;\">2<\/span> ) +\n  ggtitle( <span style=\"color: #3366ff;\">paste0<\/span> (' <span style=\"color: #008000;\">ROC Curve<\/span> ', ' <span style=\"color: #008000;\">(AUC =<\/span> ', auc, ' <span style=\"color: #008000;\">)<\/span> ')) +\n  theme_minimal()<\/strong> <\/pre>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"aligncenter wp-image-11615 \" src=\"https:\/\/statorials.org\/wp-content\/uploads\/2023\/08\/rocggplot3.png\" alt=\"Curva ROC em R usando ggplot2\" width=\"466\" height=\"466\" srcset=\"\" sizes=\"auto, \"><\/p>\n<p> <span style=\"color: #000000;\">Consulte <a href=\"https:\/\/statorials.org\/pt\/melhores-temas-ggplot2\/\" target=\"_blank\" rel=\"noopener noreferrer\">este artigo<\/a> para obter um guia com os melhores temas do ggplot2.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A regress\u00e3o log\u00edstica \u00e9 um m\u00e9todo estat\u00edstico que usamos para ajustar um modelo de regress\u00e3o quando a vari\u00e1vel de resposta \u00e9 bin\u00e1ria. Para avaliar qu\u00e3o bem um modelo de regress\u00e3o log\u00edstica se ajusta a um conjunto de dados, podemos observar as duas m\u00e9tricas a seguir: Sensibilidade: probabilidade de o modelo prever um resultado positivo para [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-1158","post","type-post","status-publish","format-standard","hentry","category-guia"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Como tra\u00e7ar uma curva ROC usando ggplot2 (com exemplos)<\/title>\n<meta name=\"description\" content=\"Este tutorial explica como tra\u00e7ar uma curva ROC em R usando ggplot2, com v\u00e1rios exemplos.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/\" \/>\n<meta property=\"og:locale\" content=\"pt_PT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Como tra\u00e7ar uma curva ROC usando ggplot2 (com exemplos)\" \/>\n<meta property=\"og:description\" content=\"Este tutorial explica como tra\u00e7ar uma curva ROC em R usando ggplot2, com v\u00e1rios exemplos.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/\" \/>\n<meta property=\"og:site_name\" content=\"Statorials\" \/>\n<meta property=\"article:published_time\" content=\"2023-07-27T11:17:42+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/statorials.org\/wp-content\/uploads\/2023\/08\/rocggplot1.png\" \/>\n<meta name=\"author\" content=\"Dr. benjamim anderson\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Escrito por\" \/>\n\t<meta name=\"twitter:data1\" content=\"Dr. benjamim anderson\" \/>\n\t<meta name=\"twitter:label2\" content=\"Tempo estimado de leitura\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutos\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/\",\"url\":\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/\",\"name\":\"Como tra\u00e7ar uma curva ROC usando ggplot2 (com exemplos)\",\"isPartOf\":{\"@id\":\"https:\/\/statorials.org\/pt\/#website\"},\"datePublished\":\"2023-07-27T11:17:42+00:00\",\"dateModified\":\"2023-07-27T11:17:42+00:00\",\"author\":{\"@id\":\"https:\/\/statorials.org\/pt\/#\/schema\/person\/e08f98e8db95e0aa9c310e1b27c9c666\"},\"description\":\"Este tutorial explica como tra\u00e7ar uma curva ROC em R usando ggplot2, com v\u00e1rios exemplos.\",\"breadcrumb\":{\"@id\":\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/#breadcrumb\"},\"inLanguage\":\"pt-PT\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/statorials.org\/pt\/curva-de-rocha-ggplot2\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Lar\",\"item\":\"https:\/\/statorials.org\/pt\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Como tra\u00e7ar uma curva roc usando ggplot2 (com exemplos)\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/statorials.org\/pt\/#website\",\"url\":\"https:\/\/statorials.org\/pt\/\",\"name\":\"Statorials\",\"description\":\"O seu guia para a literacia estat\u00edstica!\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/statorials.org\/pt\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"pt-PT\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/statorials.org\/pt\/#\/schema\/person\/e08f98e8db95e0aa9c310e1b27c9c666\",\"name\":\"Dr. benjamim anderson\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"pt-PT\",\"@id\":\"https:\/\/statorials.org\/pt\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/statorials.org\/pt\/wp-content\/uploads\/2023\/10\/Dr.-Benjamin-Anderson-96x96.jpg\",\"contentUrl\":\"https:\/\/statorials.org\/pt\/wp-content\/uploads\/2023\/10\/Dr.-Benjamin-Anderson-96x96.jpg\",\"caption\":\"Dr. benjamim anderson\"},\"description\":\"Ol\u00e1, sou Benjamin, um professor aposentado de estat\u00edstica que se tornou professor dedicado na Statorials. 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