R Data Types


title: Data Types in R

Scalars

Scalar refers to an atomic quantity that can hold only one value at a time. Scalars are the most basic data types. Some common types of scalars :

  1. Number
> x <- 5 > y <- 5.5 > class(x) [1] "numeric" > class(y) [1] "numeric" > class(x+y) [1] "numeric"
  1. Logical value
> m <- x > y # Used to check, Is x larger than y? > n <- x < y # Used to check, Is x smaller than y? > m [1] FALSE > n [1] TRUE > class(m) [1] "logical" > class(NA) # NA is another logical value: 'Not Available'/Missing Values [1] "logical"
  1. Character(string)
> a <- "1"; b <- "2.5" > a;b [1] "1" [1] "2.5" > a+b Error in a + b : non-numeric argument to binary operator > class(a) [1] "character" > class(as.numeric(a)) [1] "numeric" > class(as.character(x)) [1] "character"

Vector

Vectors are sequences of data elements of the same basic type. For example:

> o <- c(1,2,5.3,6,-2,4) # Numeric vector > p <- c("one","two","three","four","five","six") # Character vector > q <- c(TRUE,TRUE,FALSE,TRUE,FALSE,TRUE) # Logical vector > o;p;q [1] 1.0 2.0 5.3 6.0 -2.0 4.0 [1] "one" "two" "three" "four" "five" "six" [1] TRUE TRUE FALSE TRUE FALSE

Matrix

A matrix is a two-dimensional rectangular data set. The components in a matrix must be of the same basic type. For example:

> m = matrix( c('a','a','b','c','b','a'), nrow = 2, ncol = 3, byrow = TRUE) > m >[,1] [,2] [,3] [1,] "a" "a" "b" [2,] "c" "b" "a"

Data Frame

A data frame is more general than a matrix, in that different columns can have different basic data types. For example:

> d <- c(1,2,3,4) > e <- c("red", "white", "red", NA) > f <- c(TRUE,TRUE,TRUE,FALSE) > mydata <- data.frame(d,e,f) > names(mydata) <- c("ID","Color","Passed") > mydata ID Color Passed 1 1 red TRUE 2 2 white TRUE 3 3 red TRUE 4 4 <NA> FALSE

Lists

Lists are R-objects which can contain many different types of elements inside them like vectors, functions and even another list. For example:

> list1 <- list(c(2,5,3),21.3,sin) > list1 [[1]] [1] 2 5 3 [[2]] [1] 21.3 [[3]] function (x) .Primitive("sin")

Reference:

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