# Special values in R

R comes with some special values. Some of the special values in R are NA, Inf, -Inf, and NaN.

## How to do it…

The missing values are represented in R by NA. When we download data, it may have missing data and this is represented in R by NA:

z = c( 1,2,3, NA,5,NA) # NA in R is missing Data

To detect missing values, we can use the `install.packages()`

function or `is.na()`

, as shown:

`complete.cases(z) # function to detect NA`

`is.na(z) # function to detect NA`

To remove the NA values from our data, we can type the following in our active R session console window:

clean <- complete.cases(z) z[clean] # used to remove NA from data

Please note the use of square brackets (`[`

`]`

) instead of parentheses.

In R, not a number is abbreviated as NaN. The following lines will generate NaN values:

##NaN 0/0 m <- c(2/3,3/3,0/0) m

The `is.finite`

, `is.infinite`

, or `is.nan`

functions will generate logical values (`TRUE`

or `FALSE`

).

is.finite(m) is.infinite(m) is.nan(m)

The following line will generate `inf`

as a special value in R:

## infinite k = 1/0

### Tip

**Downloading the example code**

You can download the example code files for all Packt books you have purchased from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.

## How it works…

`complete.cases(z)`

is a logical vector indicating complete cases that have no missing value (NA). On the other hand, `is.na(z)`

indicates which elements are missing. In both cases, the argument is our data, a vector, or a matrix.

R also allows its users to check if any element in a matrix or a vector is NA by using the `anyNA()`

function. We can coerce or assign NA to any element of a vector using the square brackets ([ ]). The `[3]`

input instructs R to assign NA to the third element of the `dk`

vector.