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"

2. 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"

3. 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:

• Official Docs
• Data Types in R by r-bloggers