CODEWITHSUNDEEP
r
oneyellowlion
oneyellowlion

Reputation: 365

NA in List vs. Vector

Can someone explain why NA is evaluated as TRUE when it's inside a vector, but FALSE when it's an element in a list? See below.

Big thanks for any help.

> is.numeric(c(1, 2, NA)[3])
[1] TRUE
> is.numeric(list(1, 2, NA)[[3]]) 
[1] FALSE
> typeof(c(1, 2, NA)[3])
[1] "double"
typeof(list(1, 2, NA)[[3]]) 
[1] "logical"

Upvotes: 5

Views: 264

Answers (1)

akrun
akrun

Reputation: 887078

It is related to type coercion in the vector to numeric as vector can have only a single type whereas each list element can be of different type. By default, the NA is logical. According to ?NA

NA is a logical constant of length 1 which contains a missing value indicator. 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.

If we want numeric NA in a list, use NA_real_

typeof(list(1, 2, NA_real_)[[3]])
[1] "double"

Upvotes: 6

Related Questions