Selecting character(0) from a list

Question

This is (part of) the dput() output of a List that I've got.

L<-list(c("LumenVox LLC", "LumenVox LLC", "Voxware Inc", "LumenVox LLC", 
        "Voxware Inc", "Voxant Inc"),character(0), character(0), character(0), 
        character(0), c("HumanZyme Inc", "ZymeQuest Inc", "Zymetx Inc", 
        "Zymetx Inc"))
[[1]]
[1] "LumenVox LLC" "LumenVox LLC" "Voxware Inc"  "LumenVox LLC" "Voxware Inc"  "Voxant Inc"  

[[2]]
character(0)

[[3]]
character(0)

[[4]]
character(0)

[[5]]
character(0)

[[6]]
[1] "HumanZyme Inc" "ZymeQuest Inc" "Zymetx Inc"    "Zymetx Inc"

It either contains a character vector, or character(0).. I want to select only the elements that are written as character(0) but I don't know how. Could anyone help me with this?

I don't think the dupe tagged is correct as the OP is asking for something else. — akrun, Jul 22 '16 at 06:29

akrun · Accepted Answer · 2016-07-22T11:01:17.423

2

We can use Filter

Filter(Negate(length), L)

Or another option is sapply

L[!sapply(L, length)]

Or as @MartinMorgan mentioned lengths (introduced in the recent R version) can be used (which would be faster)

L[!lengths(L))

edited Jul 22 '16 at 11:01

answered Jul 22 '16 at 05:50

akrun

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oh! so, character(0) has no length. Thanks! – Darren Jul 22 '16 at 05:58
2

better to use `L[lengths(L) == 0L)` which avoids iteration over loop elements at the R level. – Martin Morgan Jul 22 '16 at 10:51

Selecting character(0) from a list

1 Answers1