{"appState":{"pageLoadApiCallsStatus":true},"articleState":{"article":{"headers":{"creationTime":"2016-03-26T07:41:04+00:00","modifiedTime":"2016-03-26T07:41:04+00:00","timestamp":"2022-09-14T17:51:21+00:00"},"data":{"breadcrumbs":[{"name":"Technology","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33512"},"slug":"technology","categoryId":33512},{"name":"Programming & Web Design","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33592"},"slug":"programming-web-design","categoryId":33592},{"name":"R","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33607"},"slug":"r","categoryId":33607}],"title":"Subsetting R Objects","strippedTitle":"subsetting r objects","slug":"subsetting-r-objects","canonicalUrl":"","seo":{"metaDescription":"Vectors, lists, and data frames play an important role in representing data in R, so being able to succinctly and correctly specify a subset of your data is imp","noIndex":0,"noFollow":0},"content":"<p>Vectors, lists, and data frames play an important role in representing data in R, so being able to succinctly and correctly specify a subset of your data is important.</p>\n<p>There are three main operators that you can use to subset your data:</p>\n<ul class=\"level-one\">\n <li><p class=\"first-para\"><span class=\"code\">$:</span><span class=\"code\"> </span>Extracts a single element by name from a list or data frame. For example, <span class=\"code\">iris$Sepal.Length</span><span class=\"code\"> </span>extracts the column <span class=\"code\">Sepal.Length</span><span class=\"code\"> </span>from the data frame <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><span class=\"code\">[[:</span><span class=\"code\"> </span>Extracts a single element by name or position from a list or data frame. For example, <span class=\"code\">iris[[</span><span class=\"code\">\"</span><span class=\"code\">Sepal.Length</span><span class=\"code\">\"</span><span class=\"code\">]]</span><span class=\"code\"> </span>extracts the column <span class=\"code\">Sepal.Length</span><span class=\"code\"> </span>from the data frame; <span class=\"code\">iris;</span><span class=\"code\"> </span><span class=\"code\">iris[[2]]</span><span class=\"code\"> </span>extracts the second element from <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><span class=\"code\">[:</span><span class=\"code\"> </span>Extracts multiple elements from a vector, array, list, or data frame. For example, <span class=\"code\">iris[, c(</span><span class=\"code\">\"</span><span class=\"code\">Sepal.Length</span><span class=\"code\">\"</span><span class=\"code\">, </span><span class=\"code\">\"</span><span class=\"code\">Species</span><span class=\"code\">\"</span><span class=\"code\">)]</span><span class=\"code\"> </span>extracts the columns <span class=\"code\">Sepal.Length</span><span class=\"code\"> </span>and <span class=\"code\">Species</span> from <span class=\"code\">iris</span>; <span class=\"code\">iris[1:10, ]</span><span class=\"code\"> </span>extracts the first ten rows from <span class=\"code\">iris</span>; and <span class=\"code\">iris[1:10, </span><span class=\"code\">\"</span><span class=\"code\">Species</span><span class=\"code\">\"</span><span class=\"code\">]</span> extracts the first ten elements of the column <span class=\"code\">Species</span><span class=\"code\"> </span><span class=\"code\">from</span><span class=\"code\"> </span><span class=\"code\">iris</span>.</p>\n </li>\n</ul>\n<p>The bracket subset operator, [, allows you to return multiple elements. You specify the subset in one of five ways:</p>\n<ul class=\"level-one\">\n <li><p class=\"first-para\"><b>Blank: </b>Returns everything. For example, <span class=\"code\">iris[]</span><span class=\"code\"> </span>returns all of <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Positive numeral: </b>Includes only these elements. For example, <span class=\"code\">iris[1:100, 5]</span><span class=\"code\"> </span>extracts the first hundred elements of the fifth column of <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Negative numeral:</b> Excludes these elements. For example, <span class=\"code\">iris[-(1:100), ]</span><span class=\"code\"> </span>excludes the first hundred rows from <span class=\"code\">iris</span>, while <span class=\"code\">iris[, -5]</span><span class=\"code\"> </span>excludes the fifth column from <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Logical:</b> Includes if <span class=\"code\">TRUE</span>; excludes if <span class=\"code\">FALSE</span>. For example, <span class=\"code\">iris[iris$Species==</span><span class=\"code\">\"</span><span class=\"code\">setosa</span><span class=\"code\">\"</span><span class=\"code\">, ]</span><span class=\"code\"> </span>extracts only those rows from <span class=\"code\">iris</span> where the <span class=\"code\">Species</span> value is <span class=\"code\">\"</span><span class=\"code\">setosa</span><span class=\"code\">\"</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Name:</b> Includes all names that match. For example, <span class=\"code\">iris[, c(</span><span class=\"code\">\"</span><span class=\"code\">Species</span><span class=\"code\">\"</span><span class=\"code\">, </span><span class=\"code\">\"</span><span class=\"code\">Petal.Width</span><span class=\"code\">\"</span><span class=\"code\">)]</span> extracts the columns <span class=\"code\">Species</span> and <span class=\"code\">Petal.Width</span> from <span class=\"code\">iris</span>.</p>\n </li>\n</ul>","description":"<p>Vectors, lists, and data frames play an important role in representing data in R, so being able to succinctly and correctly specify a subset of your data is important.</p>\n<p>There are three main operators that you can use to subset your data:</p>\n<ul class=\"level-one\">\n <li><p class=\"first-para\"><span class=\"code\">$:</span><span class=\"code\"> </span>Extracts a single element by name from a list or data frame. For example, <span class=\"code\">iris$Sepal.Length</span><span class=\"code\"> </span>extracts the column <span class=\"code\">Sepal.Length</span><span class=\"code\"> </span>from the data frame <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><span class=\"code\">[[:</span><span class=\"code\"> </span>Extracts a single element by name or position from a list or data frame. For example, <span class=\"code\">iris[[</span><span class=\"code\">\"</span><span class=\"code\">Sepal.Length</span><span class=\"code\">\"</span><span class=\"code\">]]</span><span class=\"code\"> </span>extracts the column <span class=\"code\">Sepal.Length</span><span class=\"code\"> </span>from the data frame; <span class=\"code\">iris;</span><span class=\"code\"> </span><span class=\"code\">iris[[2]]</span><span class=\"code\"> </span>extracts the second element from <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><span class=\"code\">[:</span><span class=\"code\"> </span>Extracts multiple elements from a vector, array, list, or data frame. For example, <span class=\"code\">iris[, c(</span><span class=\"code\">\"</span><span class=\"code\">Sepal.Length</span><span class=\"code\">\"</span><span class=\"code\">, </span><span class=\"code\">\"</span><span class=\"code\">Species</span><span class=\"code\">\"</span><span class=\"code\">)]</span><span class=\"code\"> </span>extracts the columns <span class=\"code\">Sepal.Length</span><span class=\"code\"> </span>and <span class=\"code\">Species</span> from <span class=\"code\">iris</span>; <span class=\"code\">iris[1:10, ]</span><span class=\"code\"> </span>extracts the first ten rows from <span class=\"code\">iris</span>; and <span class=\"code\">iris[1:10, </span><span class=\"code\">\"</span><span class=\"code\">Species</span><span class=\"code\">\"</span><span class=\"code\">]</span> extracts the first ten elements of the column <span class=\"code\">Species</span><span class=\"code\"> </span><span class=\"code\">from</span><span class=\"code\"> </span><span class=\"code\">iris</span>.</p>\n </li>\n</ul>\n<p>The bracket subset operator, [, allows you to return multiple elements. You specify the subset in one of five ways:</p>\n<ul class=\"level-one\">\n <li><p class=\"first-para\"><b>Blank: </b>Returns everything. For example, <span class=\"code\">iris[]</span><span class=\"code\"> </span>returns all of <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Positive numeral: </b>Includes only these elements. For example, <span class=\"code\">iris[1:100, 5]</span><span class=\"code\"> </span>extracts the first hundred elements of the fifth column of <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Negative numeral:</b> Excludes these elements. For example, <span class=\"code\">iris[-(1:100), ]</span><span class=\"code\"> </span>excludes the first hundred rows from <span class=\"code\">iris</span>, while <span class=\"code\">iris[, -5]</span><span class=\"code\"> </span>excludes the fifth column from <span class=\"code\">iris</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Logical:</b> Includes if <span class=\"code\">TRUE</span>; excludes if <span class=\"code\">FALSE</span>. For example, <span class=\"code\">iris[iris$Species==</span><span class=\"code\">\"</span><span class=\"code\">setosa</span><span class=\"code\">\"</span><span class=\"code\">, ]</span><span class=\"code\"> </span>extracts only those rows from <span class=\"code\">iris</span> where the <span class=\"code\">Species</span> value is <span class=\"code\">\"</span><span class=\"code\">setosa</span><span class=\"code\">\"</span>.</p>\n </li>\n <li><p class=\"first-para\"><b>Name:</b> Includes all names that match. For example, <span class=\"code\">iris[, c(</span><span class=\"code\">\"</span><span class=\"code\">Species</span><span class=\"code\">\"</span><span class=\"code\">, </span><span class=\"code\">\"</span><span class=\"code\">Petal.Width</span><span class=\"code\">\"</span><span class=\"code\">)]</span> extracts the columns <span class=\"code\">Species</span> and <span class=\"code\">Petal.Width</span> from <span class=\"code\">iris</span>.</p>\n </li>\n</ul>","blurb":"","authors":[{"authorId":9088,"name":"Andrie de Vries","slug":"andrie-de-vries","description":" <p><b>Andrie de Vries</b> is a leading R expert and Business Services Director for Revolution Analytics. With over 20 years of experience, he provides consulting and training services in the use of R. <b>Joris Meys</b> is a statistician, R programmer and R lecturer with the faculty of Bio-Engineering at the University of Ghent. ","hasArticle":false,"_links":{"self":"https://dummies-api.dummies.com/v2/authors/9088"}},{"authorId":9089,"name":"Joris Meys","slug":"joris-meys","description":" <p><b>Andrie de Vries</b> is a leading R expert and Business Services Director for Revolution Analytics. With over 20 years of experience, he provides consulting and training services in the use of R. <b>Joris Meys</b> is a statistician, R programmer and R lecturer with the faculty of Bio-Engineering at the University of Ghent. 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For Dummies","testBankPinActivationLink":"","bookOutOfPrint":false,"authorsInfo":"<p><b data-author-id=\"9088\">Andrie de Vries</b> is a leading R expert and Business Services Director for Revolution Analytics. 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With over 20 years of experience, he provides consulting and training services in the use of R. <b>Joris Meys</b> is a statistician, R programmer and R lecturer with the faculty of Bio-Engineering at the University of Ghent. 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Subsetting R Objects

By: Andrie de Vries and Joris Meys and

Updated: 03-26-2016

From The Book: R For Dummies

R For Dummies

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Vectors, lists, and data frames play an important role in representing data in R, so being able to succinctly and correctly specify a subset of your data is important.

There are three main operators that you can use to subset your data:

$: Extracts a single element by name from a list or data frame. For example, iris$Sepal.Length extracts the column Sepal.Length from the data frame iris.
[[: Extracts a single element by name or position from a list or data frame. For example, iris[["Sepal.Length"]] extracts the column Sepal.Length from the data frame; iris; iris[[2]] extracts the second element from iris.
[: Extracts multiple elements from a vector, array, list, or data frame. For example, iris[, c("Sepal.Length", "Species")] extracts the columns Sepal.Length and Species from iris; iris[1:10, ] extracts the first ten rows from iris; and iris[1:10, "Species"] extracts the first ten elements of the column Species from iris.

The bracket subset operator, [, allows you to return multiple elements. You specify the subset in one of five ways:

Blank: Returns everything. For example, iris[] returns all of iris.
Positive numeral: Includes only these elements. For example, iris[1:100, 5] extracts the first hundred elements of the fifth column of iris.
Negative numeral: Excludes these elements. For example, iris[-(1:100), ] excludes the first hundred rows from iris, while iris[, -5] excludes the fifth column from iris.
Logical: Includes if TRUE; excludes if FALSE. For example, iris[iris$Species=="setosa", ] extracts only those rows from iris where the Species value is "setosa".
Name: Includes all names that match. For example, iris[, c("Species", "Petal.Width")] extracts the columns Species and Petal.Width from iris.

About This Article

This article is from the book:

R For Dummies ,

About the book authors:

Andrie de Vries is a leading R expert and Business Services Director for Revolution Analytics. With over 20 years of experience, he provides consulting and training services in the use of R. Joris Meys is a statistician, R programmer and R lecturer with the faculty of Bio-Engineering at the University of Ghent.

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