{"id":2545,"date":"2023-07-21T19:35:49","date_gmt":"2023-07-21T19:35:49","guid":{"rendered":"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/"},"modified":"2023-07-21T19:35:49","modified_gmt":"2023-07-21T19:35:49","slug":"funcao-sigmoide-python","status":"publish","type":"post","link":"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/","title":{"rendered":"Como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em python (com exemplos)"},"content":{"rendered":"<p><\/p>\n<hr>\n<p><span style=\"color: #000000;\">Uma <a href=\"https:\/\/en.wikipedia.org\/wiki\/Sigmoid_function\" target=\"_blank\" rel=\"noopener\">fun\u00e7\u00e3o sigm\u00f3ide<\/a> \u00e9 uma fun\u00e7\u00e3o matem\u00e1tica que exibe uma curva em forma de \u201cS\u201d quando plotada.<\/span><\/p>\n<p> <span style=\"color: #000000;\">O exemplo mais comum de fun\u00e7\u00e3o sigm\u00f3ide \u00e9 a fun\u00e7\u00e3o sigm\u00f3ide log\u00edstica, que \u00e9 calculada da seguinte forma:<\/span><\/p>\n<p> <span style=\"color: #000000;\"><strong>F(x) = 1 \/ (1 + e <sup>-x<\/sup> )<\/strong><\/span><\/p>\n<p> <span style=\"color: #000000;\">A maneira mais f\u00e1cil de calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python \u00e9 usar a fun\u00e7\u00e3o <a href=\"https:\/\/docs.scipy.org\/doc\/scipy\/reference\/generated\/scipy.special.expit.html\" target=\"_blank\" rel=\"noopener\">expit()<\/a> da biblioteca <strong>SciPy<\/strong> , que usa a seguinte sintaxe b\u00e1sica:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008000;\">from<\/span> scipy. <span style=\"color: #3366ff;\">special<\/span> <span style=\"color: #008000;\">import<\/span> expit\n\n<span style=\"color: #008080;\">#calculate sigmoid function for x = 2.5\n<\/span>expire(2.5)\n<\/strong><\/pre>\n<p> <span style=\"color: #000000;\">Os exemplos a seguir mostram como usar esta fun\u00e7\u00e3o na pr\u00e1tica.<\/span><\/p>\n<h3> <span style=\"color: #000000;\"><strong>Exemplo 1: calcule a fun\u00e7\u00e3o sigm\u00f3ide para um valor<\/strong><\/span><\/h3>\n<p> <span style=\"color: #000000;\">O c\u00f3digo a seguir mostra como calcular a fun\u00e7\u00e3o sigm\u00f3ide para o valor x = 2,5:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008000;\">from<\/span> scipy. <span style=\"color: #3366ff;\">special<\/span> <span style=\"color: #008000;\">import<\/span> expit\n\n<span style=\"color: #008080;\">#calculate sigmoid function for x = 2.5\n<\/span>expire(2.5)\n\n0.9241418199787566\n<\/strong><\/pre>\n<p> <span style=\"color: #000000;\">O valor da fun\u00e7\u00e3o sigm\u00f3ide para x = 2,5 \u00e9 <strong>0,924<\/strong> .<\/span><\/p>\n<p> <span style=\"color: #000000;\">Podemos confirmar isso calculando o valor manualmente:<\/span><\/p>\n<ul>\n<li> <span style=\"color: #000000;\">F(x) = 1 \/ (1 + e <sup>-x<\/sup> )<\/span><\/li>\n<li> <span style=\"color: #000000;\">F(x) = 1 \/ (1 + e <sup>-2,5<\/sup> )<\/span><\/li>\n<li> <span style=\"color: #000000;\">F(x) = 1 \/ (1 + 0,082)<\/span><\/li>\n<li> <span style=\"color: #000000;\">F(x) = <strong>0,924<\/strong><\/span><\/li>\n<\/ul>\n<h3> <span style=\"color: #000000;\"><strong>Exemplo 2: Calcule a fun\u00e7\u00e3o sigm\u00f3ide para v\u00e1rios valores<\/strong><\/span><\/h3>\n<p> <span style=\"color: #000000;\">O c\u00f3digo a seguir mostra como calcular a fun\u00e7\u00e3o sigm\u00f3ide para v\u00e1rios valores de x de uma s\u00f3 vez:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008080;\"><span style=\"color: #000000;\"><span style=\"color: #008000;\">from<\/span> scipy. <span style=\"color: #3366ff;\">special<\/span> <span style=\"color: #008000;\">import<\/span> expit\n<\/span>\n#define list of values\n<span style=\"color: #000000;\">values = [-2, -1, 0, 1, 2]\n\n<span style=\"color: #008080;\">#calculate sigmoid function for each value in list\n<\/span>expire(values)\n\narray([0.11920292, 0.26894142, 0.5, 0.73105858, 0.88079708])\n<\/span><\/span><\/strong><\/pre>\n<h3> <span style=\"color: #000000;\"><strong>Exemplo 3: tra\u00e7ando a fun\u00e7\u00e3o sigm\u00f3ide para um intervalo de valores<\/strong><\/span><\/h3>\n<p> <span style=\"color: #000000;\">O c\u00f3digo a seguir mostra como plotar os valores de uma fun\u00e7\u00e3o sigm\u00f3ide para um intervalo de valores x usando <a href=\"https:\/\/matplotlib.org\/\" target=\"_blank\" rel=\"noopener\">matplotlib<\/a> :<\/span> <\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong><span style=\"color: #008080;\"><span style=\"color: #000000;\"><span style=\"color: #008000;\">import <span style=\"color: #000000;\">matplotlib. <span style=\"color: #3366ff;\">pyplot<\/span> <span style=\"color: #008000;\">as<\/span> plt\n<span style=\"color: #008000;\">from<\/span> scipy. <span style=\"color: #3366ff;\">special<\/span> <span style=\"color: #008000;\">import<\/span> expit\n<span style=\"color: #008000;\">import<\/span> numpy <span style=\"color: #008000;\">as<\/span> np\n\n<span style=\"color: #008080;\">#define range of x-values\n<\/span>x = np. <span style=\"color: #3366ff;\">linspace<\/span> (-10, 10, 100)\n\n<span style=\"color: #008080;\">#calculate sigmoid function for each x-value\n<\/span>y = expire(x)\n  \n<span style=\"color: #008080;\">#createplot\n<\/span>plt. <span style=\"color: #3366ff;\">plot<\/span> (x, y)\nplt. <span style=\"color: #3366ff;\">xlabel<\/span> (' <span style=\"color: #ff0000;\">x<\/span> ')\nplt. <span style=\"color: #3366ff;\">ylabel<\/span> (' <span style=\"color: #ff0000;\">F(x)<\/span> ')\n\n<span style=\"color: #008080;\">#displayplot\n<\/span>plt. <span style=\"color: #3366ff;\">show<\/span> ()\n<\/span><\/span><\/span><\/span><\/strong><\/pre>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"aligncenter wp-image-22606\" src=\"https:\/\/statorials.org\/wp-content\/uploads\/2023\/08\/sigmoide_python.jpg\" alt=\"fun\u00e7\u00e3o sigm\u00f3ide em Python\" width=\"495\" height=\"377\" srcset=\"\" sizes=\"auto, \"><\/p>\n<p> <span style=\"color: #000000;\">Observe que o gr\u00e1fico mostra a curva em forma de \u201cS\u201d caracter\u00edstica de uma fun\u00e7\u00e3o sigm\u00f3ide.<\/span><\/p>\n<h3> <span style=\"color: #000000;\"><strong>Recursos adicionais<\/strong><\/span><\/h3>\n<p> <span style=\"color: #000000;\">Os tutoriais a seguir explicam como realizar outras opera\u00e7\u00f5es comuns em Python:<\/span><\/p>\n<p> <a href=\"https:\/\/statorials.org\/pt\/regressao-logistica-python\/\" target=\"_blank\" rel=\"noopener\">Como realizar regress\u00e3o log\u00edstica em Python<\/a><br \/> <a href=\"https:\/\/statorials.org\/pt\/tracar-regressao-logistica-em-python\/\" target=\"_blank\" rel=\"noopener\">Como tra\u00e7ar uma curva de regress\u00e3o log\u00edstica em Python<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Uma fun\u00e7\u00e3o sigm\u00f3ide \u00e9 uma fun\u00e7\u00e3o matem\u00e1tica que exibe uma curva em forma de \u201cS\u201d quando plotada. O exemplo mais comum de fun\u00e7\u00e3o sigm\u00f3ide \u00e9 a fun\u00e7\u00e3o sigm\u00f3ide log\u00edstica, que \u00e9 calculada da seguinte forma: F(x) = 1 \/ (1 + e -x ) A maneira mais f\u00e1cil de calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python [&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-2545","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 calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python (com exemplos) - Estatologia<\/title>\n<meta name=\"description\" content=\"Este tutorial explica como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python, 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\/funcao-sigmoide-python\/\" \/>\n<meta property=\"og:locale\" content=\"pt_PT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python (com exemplos) - Estatologia\" \/>\n<meta property=\"og:description\" content=\"Este tutorial explica como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python, com v\u00e1rios exemplos.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/\" \/>\n<meta property=\"og:site_name\" content=\"Statorials\" \/>\n<meta property=\"article:published_time\" content=\"2023-07-21T19:35:49+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/statorials.org\/wp-content\/uploads\/2023\/08\/sigmoide_python.jpg\" \/>\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\/funcao-sigmoide-python\/\",\"url\":\"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/\",\"name\":\"Como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python (com exemplos) - Estatologia\",\"isPartOf\":{\"@id\":\"https:\/\/statorials.org\/pt\/#website\"},\"datePublished\":\"2023-07-21T19:35:49+00:00\",\"dateModified\":\"2023-07-21T19:35:49+00:00\",\"author\":{\"@id\":\"https:\/\/statorials.org\/pt\/#\/schema\/person\/e08f98e8db95e0aa9c310e1b27c9c666\"},\"description\":\"Este tutorial explica como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em Python, com v\u00e1rios exemplos.\",\"breadcrumb\":{\"@id\":\"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/#breadcrumb\"},\"inLanguage\":\"pt-PT\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/statorials.org\/pt\/funcao-sigmoide-python\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Lar\",\"item\":\"https:\/\/statorials.org\/pt\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Como calcular uma fun\u00e7\u00e3o sigm\u00f3ide em python (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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