{"id":3070,"date":"2015-07-08T08:30:55","date_gmt":"2015-07-08T07:30:55","guid":{"rendered":"https:\/\/abcdr.guyader.pro\/?p=3070"},"modified":"2018-04-08T00:01:40","modified_gmt":"2018-04-07T23:01:40","slug":"comment-faire-des-comptages-dans-un-data-frame-apply-lapply-sapply-which-3","status":"publish","type":"post","link":"https:\/\/thinkr.fr\/abcdr\/comment-faire-des-comptages-dans-un-data-frame-apply-lapply-sapply-which-3\/","title":{"rendered":"Comment faire des comptages dans un data.frame ? apply, lapply, sapply, which"},"content":{"rendered":"<p>Les fonctions de la famille <strong>apply(<\/strong>) et la fonction <strong>which()<\/strong> peuvent permettre de compter les \u00e9l\u00e9ments identiques, n\u00e9gatifs, positifs ou encore sup\u00e9rieurs ou inf\u00e9rieurs \u00e0 une certaine valeur dans un data.frame.<\/p>\n<pre><code><br \/>iris<br \/># iris, un tableau de donn\u00e9es\n\nm &lt;- matrix(data=cbind(rnorm(30, 0), rnorm(30, 2), rnorm(30, 5)), nrow=30, ncol=3)\n\n# m, une matrice de donn\u00e9es <br \/> <\/code><\/pre>\n<p>Calculer le nombre d\u2019\u00e9l\u00e9ments identiques :<\/p>\n<pre><code><br \/>### Dans un tableau :<br \/>lapply (iris, function(x) length(unique(x))) # retourne une liste\n\nsapply (iris, function(x) length(unique(x))) # retourne un vecteur num\u00e9rique\n\n### Dans une matrice :\n\napply (m, 2,function(x) length(unique(x))) #retourne des entiers <br \/> <\/code><\/pre>\n<p>Calculer le nombre d\u2019\u00e9l\u00e9ments sup\u00e9rieurs ou inf\u00e9rieur \u00e0 une certaine valeur :<\/p>\n<pre><code><br \/>### Dans un tableau :<br \/>iris2 &lt;- as.matrix(iris) # On convertie la base de donn\u00e9es en matrice\n\niris2[,1] &lt;- as.numeric(iris2[,1]) # On convertie la colonne en donn\u00e9es num\u00e9riques\n\nlength(which(iris2[,1]&gt;5)) # On obtient le nombre s\u00e9pales dont la longueur est sup\u00e9rieur \u00e0 5\n\n### Dans une matrice :\n\napply(m, 2, function(x) length(x[x&lt;0])) # Nombre d\u2019\u00e9l\u00e9ments n\u00e9gatifs\n\napply(m, 2, function(x) length(x[x &gt; 1.5])) # Nombre d\u2019\u00e9l\u00e9ments sup\u00e9rieur \u00e0 1,5<br \/> <\/code><\/pre>\n<p>\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Les fonctions de la famille apply() et la fonction which() peuvent permettre de compter les \u00e9l\u00e9ments identiques, n\u00e9gatifs, positifs ou encore sup\u00e9rieurs ou inf\u00e9rieurs \u00e0 une certaine valeur dans un data.frame. iris# iris, un tableau de donn\u00e9es m &lt;- matrix(data=cbind(rnorm(30, 0), rnorm(30, 2), rnorm(30, 5)), nrow=30, ncol=3) # m, une matrice de donn\u00e9es Calculer le nombre d\u2019\u00e9l\u00e9ments identiques : ### Dans un tableau :lapply (iris, function(x) length(unique(x))) # retourne une liste sapply (iris, function(x) length(unique(x))) # retourne un vecteur num\u00e9rique ### Dans une matrice : apply (m, 2,function(x) length(unique(x))) #retourne des entiers Calculer le nombre d\u2019\u00e9l\u00e9ments sup\u00e9rieurs ou inf\u00e9rieur \u00e0 une certaine valeur : ###<a class=\"more-link\" href=\"https:\/\/thinkr.fr\/abcdr\/comment-faire-des-comptages-dans-un-data-frame-apply-lapply-sapply-which-3\/\">Read More &rarr;<\/a><\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"content-type":"","rop_custom_images_group":[],"rop_custom_messages_group":[],"rop_publish_now":"initial","rop_publish_now_accounts":{"twitter_399453572_399453572":""},"rop_publish_now_history":[],"rop_publish_now_status":"pending","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[8],"tags":[],"class_list":{"0":"entry","1":"post","2":"publish","3":"author-helene","4":"post-3070","6":"format-standard","7":"category-fonctions-utiles"},"acf":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p9O7Sx-Nw","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts\/3070","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/comments?post=3070"}],"version-history":[{"count":2,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts\/3070\/revisions"}],"predecessor-version":[{"id":4261,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts\/3070\/revisions\/4261"}],"wp:attachment":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/media?parent=3070"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/categories?post=3070"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/tags?post=3070"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}