haven (version 2.1.1)

tagged_na: "Tagged" missing values

Description

"Tagged" missing values work exactly like regular R missing values except that they store one additional byte of information a tag, which is usually a letter ("a" to "z"). When by loading a SAS and Stata file, the tagged missing values always use lower case values.

Usage

tagged_na(...)
na_tag(x)
is_tagged_na(x, tag = NULL)
format_tagged_na(x, digits = getOption("digits"))
print_tagged_na(x, digits = getOption("digits"))

Arguments

...

Vectors containing single character. The letter will be used to "tag" the missing value.

x

A numeric vector

tag

If NULL, will only return true if the tag has this value.

digits

Number of digits to use in string representation

Details

format_tagged_na() and print_tagged_na() format tagged NA's as NA(a), NA(b), etc.

Examples

# NOT RUN {
x <- c(1:5, tagged_na("a"), tagged_na("z"), NA)

# Tagged NA's work identically to regular NAs
x
is.na(x)

# To see that they're special, you need to use na_tag(),
# is_tagged_na(), or print_tagged_na():
is_tagged_na(x)
na_tag(x)
print_tagged_na(x)

# You can test for specific tagged NAs with the second argument
is_tagged_na(x, "a")

# Because the support for tagged's NAs is somewhat tagged on to R,
# the left-most NA will tend to be preserved in arithmetic operations.
na_tag(tagged_na("a") + tagged_na("z"))
# }