[R] R Help

[Marc Schwartz]

on 02/12/2009 10:07 PM Stuart Jaffe wrote:
> Hi,
>    I have a list of numbers (classified as a list) that contains integer(0)
> empty vectors. How do I convert those integer(0) into NAs? Thanks

Presuming that you are referring to a list along the lines of:

L <- list(1:5, integer(0), 2:4, integer(0), integer(0), 3:7)

> L
[[1]]
[1] 1 2 3 4 5

[[2]]
integer(0)

[[3]]
[1] 2 3 4

[[4]]
integer(0)

[[5]]
integer(0)

[[6]]
[1] 3 4 5 6 7



You could use:

> lapply(L, function(x) if (length(x) == 0)  NA else x)
[[1]]
[1] 1 2 3 4 5

[[2]]
[1] NA

[[3]]
[1] 2 3 4

[[4]]
[1] NA

[[5]]
[1] NA

[[6]]
[1] 3 4 5 6 7


The key is that integer(0) has length 0.

HTH,

Marc Schwartz