{"id":1824,"date":"2023-07-24T20:30:21","date_gmt":"2023-07-24T20:30:21","guid":{"rendered":"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/"},"modified":"2023-07-24T20:30:21","modified_gmt":"2023-07-24T20:30:21","slug":"standardizzare-i-dati-python","status":"publish","type":"post","link":"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/","title":{"rendered":"Come standardizzare i dati in python: con esempi"},"content":{"rendered":"<p><\/p>\n<hr>\n<p><span style=\"color: #000000;\"><strong>Standardizzare<\/strong> un set di dati significa ridimensionare tutti i valori nel set di dati in modo tale che il valore medio sia 0 e la deviazione standard sia 1.<\/span><\/p>\n<p> <span style=\"color: #000000;\">Usiamo la seguente formula per normalizzare i valori in un set di dati:<\/span><\/p>\n<p> <span style=\"color: #000000;\"><strong>x <sub>nuovo<\/sub> = (x <sub>i<\/sub> \u2013 <span style=\"text-decoration: overline;\">x<\/span> ) \/ s<\/strong><\/span><\/p>\n<p> <span style=\"color: #000000;\">Oro:<\/span><\/p>\n<ul>\n<li> <span style=\"color: #000000;\"><strong>x <sub>i<\/sub><\/strong> : l&#8217;i <sup>-esimo<\/sup> valore del set di dati<\/span><\/li>\n<li> <span style=\"color: #000000;\"><strong><span style=\"text-decoration: overline;\">x<\/span><\/strong> : Il campione significa<\/span><\/li>\n<li> <span style=\"color: #000000;\"><strong>s<\/strong> : la deviazione standard del campione<\/span><\/li>\n<\/ul>\n<p> <span style=\"color: #000000;\">Possiamo usare la seguente sintassi per normalizzare rapidamente tutte le colonne in un DataFrame panda in Python:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <strong>(df- <span style=\"color: #3366ff;\">df.mean<\/span> ())\/df. <span style=\"color: #3366ff;\">std<\/span> ()\n<\/strong><\/pre>\n<p> <span style=\"color: #000000;\">Gli esempi seguenti mostrano come utilizzare questa sintassi nella pratica.<\/span><\/p>\n<h3> <span style=\"color: #000000;\"><strong>Esempio 1: standardizzare tutte le colonne DataFrame<\/strong><\/span><\/h3>\n<p> <span style=\"color: #000000;\">Il codice seguente mostra come standardizzare tutte le colonne in un DataFrame panda:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <b><span style=\"color: #008000;\">import<\/span> pandas <span style=\"color: #008000;\">as<\/span> pd\n\n<span style=\"color: #008080;\">#create data frame\n<\/span>df = pd. <span style=\"color: #3366ff;\">DataFrame<\/span> ({' <span style=\"color: #ff0000;\">y<\/span> ': [8, 12, 15, 14, 19, 23, 25, 29],\n                   ' <span style=\"color: #ff0000;\">x1<\/span> ': [5, 7, 7, 9, 12, 9, 9, 4],\n                   ' <span style=\"color: #ff0000;\">x2<\/span> ': [11, 8, 10, 6, 6, 5, 9, 12],\n                   ' <span style=\"color: #ff0000;\">x3<\/span> ': [2, 2, 3, 2, 5, 5, 7, 9]})\n\n<span style=\"color: #008080;\">#view data frame\n<\/span>df\n\n\ty x1 x2 x3\n0 8 5 11 2\n1 12 7 8 2\n2 15 7 10 3\n3 14 9 6 2\n4 19 12 6 5\n5 23 9 5 5\n6 25 9 9 7\n7 29 4 12 9\n\n<span style=\"color: #008080;\">#standardize the values in each column\n<\/span>df_new = (df- <span style=\"color: #3366ff;\">df.mean<\/span> ())\/df. <span style=\"color: #3366ff;\">std<\/span> ()\n\n<span style=\"color: #008080;\">#view new data frame\n<\/span>df_new\n\n\t        y x1 x2 x3\n0 -1.418032 -1.078639 1.025393 -0.908151\n1 -0.857822 -0.294174 -0.146485 -0.908151\n2 -0.437664 -0.294174 0.634767 -0.525772\n3 -0.577717 0.490290 -0.927736 -0.908151\n4 0.122546 1.666987 -0.927736 0.238987\n5 0.682756 0.490290 -1.318362 0.238987\n6 0.962861 0.490290 0.244141 1.003746\n7 1.523071 -1.470871 1.416019 1.768505<\/b><\/pre>\n<p> <span style=\"color: #000000;\">Possiamo verificare che la media e la deviazione standard di ciascuna colonna sono rispettivamente pari a 0 e 1:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <b><span style=\"color: #008080;\">#view mean of each column\n<\/span>df_new. <span style=\"color: #3366ff;\">mean<\/span> ()\n\ny 0.000000e+00\nx1 2.775558e-17\nx2 -4.163336e-17\nx3 5.551115e-17\ndtype:float64\n\n<span style=\"color: #008080;\">#view standard deviation of each column\n<\/span>df_new. <span style=\"color: #3366ff;\">std<\/span> ()\n\ny 1.0\nx1 1.0\nx2 1.0\nx3 1.0\ndtype:float64\n<\/b><\/pre>\n<h3> <span style=\"color: #000000;\"><strong>Esempio 2: normalizzare colonne DataFrame specifiche<\/strong><\/span><\/h3>\n<p> <span style=\"color: #000000;\">A volte potresti voler normalizzare solo colonne specifiche in un DataFrame.<\/span><\/p>\n<p> <span style=\"color: #000000;\">Ad esempio, per molti algoritmi di machine learning, potresti voler standardizzare solo le variabili predittive prima di adattare un determinato modello ai dati.<\/span><\/p>\n<p> <span style=\"color: #000000;\">Il codice seguente mostra come standardizzare colonne specifiche in un DataFrame panda:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <b><span style=\"color: #008000;\">import<\/span> pandas <span style=\"color: #008000;\">as<\/span> pd\n\n<span style=\"color: #008080;\">#create data frame\n<\/span>df = pd. <span style=\"color: #3366ff;\">DataFrame<\/span> ({' <span style=\"color: #ff0000;\">y<\/span> ': [8, 12, 15, 14, 19, 23, 25, 29],\n                   ' <span style=\"color: #ff0000;\">x1<\/span> ': [5, 7, 7, 9, 12, 9, 9, 4],\n                   ' <span style=\"color: #ff0000;\">x2<\/span> ': [11, 8, 10, 6, 6, 5, 9, 12],\n                   ' <span style=\"color: #ff0000;\">x3<\/span> ': [2, 2, 3, 2, 5, 5, 7, 9]})\n\n<span style=\"color: #008080;\">#view data frame\n<\/span>df\n\n\ty x1 x2 x3\n0 8 5 11 2\n1 12 7 8 2\n2 15 7 10 3\n3 14 9 6 2\n4 19 12 6 5\n5 23 9 5 5\n6 25 9 9 7\n7 29 4 12 9\n\n<span style=\"color: #008080;\">#define predictor variable columns<\/span>\ndf_x = df[[' <span style=\"color: #ff0000;\">x1<\/span> ', ' <span style=\"color: #ff0000;\">x2<\/span> ', ' <span style=\"color: #ff0000;\">x3<\/span> ']]\n\n<span style=\"color: #008080;\">#standardize the values for each predictor variable\n<\/span>df[[' <span style=\"color: #ff0000;\">x1<\/span> ',' <span style=\"color: #ff0000;\">x2<\/span> ',' <span style=\"color: #ff0000;\">x3<\/span> ']] = (df_x- <span style=\"color: #3366ff;\">df_x.mean<\/span> ())\/df_x. <span style=\"color: #3366ff;\">std<\/span> ()\n\n<span style=\"color: #008080;\">#view new data frame\n<\/span>df\n\n         y x1 x2 x3\n0 8 -1.078639 1.025393 -0.908151\n1 12 -0.294174 -0.146485 -0.908151\n2 15 -0.294174 0.634767 -0.525772\n3 14 0.490290 -0.927736 -0.908151\n4 19 1.666987 -0.927736 0.238987\n5 23 0.490290 -1.318362 0.238987\n6 25 0.490290 0.244141 1.003746\n7 29 -1.470871 1.416019 1.768505<\/b><\/pre>\n<p> <span style=\"color: #000000;\">Tieni presente che la colonna &#8220;y&#8221; rimane invariata, ma le colonne &#8220;x1&#8221;, &#8220;x2&#8221; e &#8220;x3&#8221; sono tutte standardizzate.<\/span><\/p>\n<p> <span style=\"color: #000000;\">Possiamo verificare che la media e la deviazione standard di ciascuna colonna di variabili predittive sono rispettivamente uguali a 0 e 1:<\/span><\/p>\n<pre style=\"background-color: #ececec; font-size: 15px;\"> <b><span style=\"color: #008080;\">#view mean of each predictor variable column\n<\/span>df[[' <span style=\"color: #ff0000;\">x1<\/span> ', ' <span style=\"color: #ff0000;\">x2<\/span> ', ' <span style=\"color: #ff0000;\">x3<\/span> ']]. <span style=\"color: #3366ff;\">mean<\/span> ()\n\nx1 2.775558e-17\nx2 -4.163336e-17\nx3 5.551115e-17\ndtype:float64\n\n<span style=\"color: #008080;\">#view standard deviation of each predictor variable column\n<\/span>df[[' <span style=\"color: #ff0000;\">x1<\/span> ', ' <span style=\"color: #ff0000;\">x2<\/span> ', ' <span style=\"color: #ff0000;\">x3<\/span> ']]. <span style=\"color: #3366ff;\">std<\/span> ()\n\nx1 1.0\nx2 1.0\nx3 1.0\ndtype:float64<\/b><\/pre>\n<h3> <strong><span style=\"color: #000000;\">Risorse addizionali<\/span><\/strong><\/h3>\n<p> <a href=\"https:\/\/statorials.org\/it\/normalizza-le-colonne-dei-frame-di-dati-dei-panda\/\" target=\"_blank\" rel=\"noopener\">Come normalizzare le colonne in un Pandas DataFrame<\/a><br \/> <a href=\"https:\/\/statorials.org\/it\/rimuovere-i-valori-anomali-di-python\/\" target=\"_blank\" rel=\"noopener\">Come rimuovere i valori anomali in Python<\/a><br \/> <a href=\"https:\/\/statorials.org\/it\/standardizzazione-vs-normalizzazione\/\" target=\"_blank\" rel=\"noopener\">Standardizzazione o normalizzazione: qual \u00e8 la differenza?<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Standardizzare un set di dati significa ridimensionare tutti i valori nel set di dati in modo tale che il valore medio sia 0 e la deviazione standard sia 1. Usiamo la seguente formula per normalizzare i valori in un set di dati: x nuovo = (x i \u2013 x ) \/ s Oro: x i [&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":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Come standardizzare i dati in Python: con esempi<\/title>\n<meta name=\"description\" content=\"Questo tutorial spiega come standardizzare i dati in Python, con diversi esempi.\" \/>\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\/it\/standardizzare-i-dati-python\/\" \/>\n<meta property=\"og:locale\" content=\"it_IT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Come standardizzare i dati in Python: con esempi\" \/>\n<meta property=\"og:description\" content=\"Questo tutorial spiega come standardizzare i dati in Python, con diversi esempi.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/\" \/>\n<meta property=\"og:site_name\" content=\"Statorials\" \/>\n<meta property=\"article:published_time\" content=\"2023-07-24T20:30:21+00:00\" \/>\n<meta name=\"author\" content=\"Benjamin anderson\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Benjamin anderson\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minuti\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/\",\"url\":\"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/\",\"name\":\"Come standardizzare i dati in Python: con esempi\",\"isPartOf\":{\"@id\":\"https:\/\/statorials.org\/it\/#website\"},\"datePublished\":\"2023-07-24T20:30:21+00:00\",\"dateModified\":\"2023-07-24T20:30:21+00:00\",\"author\":{\"@id\":\"https:\/\/statorials.org\/it\/#\/schema\/person\/0896f191fb9fb019f2cd8623112cb3ae\"},\"description\":\"Questo tutorial spiega come standardizzare i dati in Python, con diversi esempi.\",\"breadcrumb\":{\"@id\":\"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/#breadcrumb\"},\"inLanguage\":\"it-IT\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/statorials.org\/it\/standardizzare-i-dati-python\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Casa\",\"item\":\"https:\/\/statorials.org\/it\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Come standardizzare i dati in python: con esempi\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/statorials.org\/it\/#website\",\"url\":\"https:\/\/statorials.org\/it\/\",\"name\":\"Statorials\",\"description\":\"La tua guida all&#039;alfabetizzazione statistica!\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/statorials.org\/it\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"it-IT\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/statorials.org\/it\/#\/schema\/person\/0896f191fb9fb019f2cd8623112cb3ae\",\"name\":\"Benjamin anderson\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"it-IT\",\"@id\":\"https:\/\/statorials.org\/it\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/statorials.org\/it\/wp-content\/uploads\/2023\/10\/Dr.-Benjamin-Anderson-96x96.jpg\",\"contentUrl\":\"https:\/\/statorials.org\/it\/wp-content\/uploads\/2023\/10\/Dr.-Benjamin-Anderson-96x96.jpg\",\"caption\":\"Benjamin anderson\"},\"description\":\"Ciao, sono Benjamin, un professore di statistica in pensione diventato insegnante dedicato di Statorials. 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