Missing values are represented in R with the general symbol
NA. They can be inserted in almost all data containers: all
atomic vectors except raw vectors can contain missing values. To
achieve this, R automatically converts the general NA symbol to a
typed missing value appropriate for the target vector. The objects
provided here are aliases for those typed NA objects.
na_lgl na_int na_dbl na_chr na_cpl
Format
An object of class logical of length 1.
Details
Typed missing values are necessary because R needs sentinel values
of the same type (i.e. the same machine representation of the data)
as the containers into which they are inserted. The official typed
missing values are NA_integer_, NA_real_, NA_character_ and
NA_complex_. The missing value for logical vectors is simply the
default NA. The aliases provided in rlang are consistently named
and thus simpler to remember. Also, na_lgl is provided as an
alias to NA that makes intent clearer.
Since na_lgl is the default NA, expressions such as c(NA, NA)
yield logical vectors as no data is available to give a clue of the
target type. In the same way, since lists and environments can
contain any types, expressions like list(NA) store a logical
NA.
Life cycle
These shortcuts might be moved to the vctrs package at some point. This is why they are marked as questioning.
Examples
typeof(NA)#> [1] "logical"typeof(na_lgl)#> [1] "logical"typeof(na_int)#> [1] "integer"# Note that while the base R missing symbols cannot be overwritten, # that's not the case for rlang's aliases: na_dbl <- NA typeof(na_dbl)#> [1] "logical"