`isNA.Rd`

Check if an object is NA. Always return TRUE of FALSE, a logical vector of length one.

isNA(x)

x | any R object. |
---|

`isNA`

returns TRUE if the argument is a single NA, i.e. it has
length one and represents an NA value. In any other case `isNA`

returns FALSE.

`isNA`

is suitable for use in conditional constructs since it
always returns a single value which is never NA.

Note that `identical()`

distinguishes different types
of NA, i.e. `identical(x, NA)`

is TRUE only if `x`

is NA
(logical).

TRUE or FALSE

`isTRUE`

, `is.na`

, `identical`

v <- c(1, NA, 3) isNA(v[2]) # TRUE#> [1] TRUE## identical() distinguishes different types of NA: class(v) # "numeric", not "integer"#> [1] "numeric"identical(v[2], NA) # FALSE, NA on its own is "logical"#> [1] FALSEidentical(v[2], NA_integer_) # FALSE#> [1] FALSEidentical(v[2], NA_real_) # TRUE#> [1] TRUEvi <- c(1L, NA_integer_, 3L) isNA(vi[2]) # TRUE#> [1] TRUEclass(vi) # "integer"#> [1] "integer"identical(vi[2], NA_integer_) # TRUE#> [1] TRUEidentical(vi[2], NA_real_) # FALSE#> [1] FALSE## is.na(NULL) would give a warning isNA(NULL) # FALSE#> [1] FALSE## a length zero object is not NA, so isNA() returns FALSE: isNA(logical(0)) # FALSE#> [1] FALSE## is.na() has a different remit and returns a 0-length vector: is.na(logical(0)) # logical(0)#> logical(0)