Not Available / Missing Values

Several types of atomic vectors (logical, integer, double, complex, character) can contain special "not available" or "missing" values, which are displayed as NA. Most operations on an NA value produce an NA.

Usage

NA NA_integer_ NA_real_ NA_complex_ NA_character_ NaN

is.na(x) ## S3 method for class 'data.frame': is.na(x) ## S3 method for class 'POSIXlt': is.na(x)

is.na(x) <- value ## Default S3 method: is.na(x) <- value ## S3 method for class 'factor': is.na(x) <- value

Arguments

Details

NA is a logical vector containing a single logical missing value. NA_integer_, NA_real_, NA_complex_, and NA_character_ contain the missing values for integers, doubles, complex, and character vectors, respectively.
NaN is a second kind of missing double value, the so-called "Not a Number" value. This can be produced by numerical computation. For example, the computations 0/0 and Inf - Inf both produce the result NaN. is.na returns TRUE both for NA and NaN values. is.nan returns TRUE for NaN values, but FALSE for other NA values.
is.na is used to test for missing values. It is a generic, and some S3 methods are implemented. Note that the logical expression x == NA is different from is.na(x). Its value is a vector of the same length as x, all of whose values are NA.
is.na<- is used to set a subset of x to NA. It is a generic, and some S3 methods are implemented.
is.na.data.frame returns a matrix with the same column names as x, where each column is the result of applying is.na to the corresponding column of x.

is.na	returns a logical vector of the same length as x, containing TRUE for every missing value in x, and FALSE for every non-missing value.
is.na<-	returns the modified variable. Any attributes from the original x variable, such as the dim attribute of a matrix, are maintained.

NA; NA_integer_; NA_real_; NA_complex_; NA_character_ # NA values of different types print the same: # [1] NA # [1] NA # [1] NA # [1] NA # [1] NA

is.na(NA) # [1] TRUE is.na(NaN) # [1] TRUE is.nan(NA) # [1] FALSE is.nan(NaN) # [1] TRUE

x <- c( 1, 3, NA, 5, NA ) is.na(x) # [1] FALSE FALSE TRUE FALSE TRUE is.na(x) <- 2 # Set the second element to NA is.na(x) # [1] FALSE TRUE TRUE FALSE TRUE

x <- factor(c("a", "b", "c", NA, "b")) is.na(x) # [1] FALSE FALSE FALSE TRUE FALSE is.na(x) <- 1:2 # Set the first and second element to NA is.na(x) # [1] TRUE TRUE FALSE TRUE FALSE

x <- 1:5 is.na(x) <- x>3 # specify elements with logical vector is.na(x) # [1] FALSE FALSE FALSE TRUE TRUE

x <- data.frame(x1=c(1,2,3), x2=c(NA,5,6), x3=c(7,NA,9)) # Return a logical matrix x with logical columns indicating NA elements is.na(x) # returns a logical matrix indicating NA elements in x # x1 x2 x3 # [1,] FALSE TRUE FALSE # [2,] FALSE FALSE TRUE # [3,] FALSE FALSE FALSE is.na(x) <- 2 # Set all elements of the second column to NA

x	any object.
value	a vector of indices or a logical vector specifying the elements to be set to NA.

Description

Usage

Arguments

Details