missing
Missing values
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.
- Keywords
- datasets
Usage
na_lglna_int
na_dbl
na_chr
na_cpl
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
.
Format
An object of class logical
of length 1.
See Also
The vector-along family to create typed vectors filled with missing values.
Examples
# NOT RUN {
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)
# }