メモ：NAにもいろいろある

R

なにこれ。

NA_integer_
NA_real_
NA_complex_
NA_character_

?NAでヘルプは見れるけどよく分からない。

NA can be coerced to any other vector type except raw. There are also constants NA_integer_, NA_real_, NA_complex_ and NA_character_ of the other atomic vector types which support missing values: all of these are reserved words in the R language.

違うというのはまあわかる。

is(NA)
#> [1] "logical" "vector" 

is(NA_integer_)
#> [1] "integer"             "numeric"             "vector"              "data.frameRowLabels"