missing
Missing values
Description
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.
Usage
na_lgl na_int na_dbl na_chr na_cpl
Format
An object of class logical of length 1.
An object of class integer of length 1.
An object of class numeric of length 1.
An object of class character of length 1.
An object of class complex 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) typeof(na_lgl) typeof(na_int) # 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)