Re: [R] list of lists, is this element empty

2014-12-21 Thread William Dunlap
Your 'x' has length 2, so x[[3]] cannot be calculated ('subscript out of bounds' is what I get). You can check for this with length(x)3. In general, you want to be more precise: 'does not have a value', 'is NULL', and 'is empty' are not synonymous. I'm not sure what 'does not have a value'

[R] list of lists, is this element empty

2014-12-20 Thread Ragia Ibrahim
Hello, Kindly I have a list of lists as follow x [[1]] [1] 7 [[2]] [1] 3 4 5 as showen x[[3]] does not have a value and it has NULL, how can I check on this how to test if x[[3]] is empty. thanks in advance Ragia [[alternative HTML version

Re: [R] list of lists, is this element empty

2014-12-20 Thread Ben Tupper
Hi, On Dec 20, 2014, at 10:58 AM, Ragia Ibrahim ragi...@hotmail.com wrote: Hello, Kindly I have a list of lists as follow x [[1]] [1] 7 [[2]] [1] 3 4 5 as showen x[[3]] does not have a value and it has NULL, how can I check on this how to test if x[[3]] is empty. In general

Re: [R] list of lists, is this element empty

2014-12-20 Thread Rui Barradas
Hello, Your list seems to have only 2 elements. You can check this with length(x) Or you can try lapply(x, is.null) Hope this helps, Rui Barradas Em 20-12-2014 15:58, Ragia Ibrahim escreveu: Hello, Kindly I have a list of lists as follow x [[1]] [1] 7 [[2]] [1] 3 4 5 as showen x[[3]]

Re: [R] list of lists, is this element empty

2014-12-20 Thread Boris Steipe
This can be tricky, because depending on what the missing object is, you can get either NULL, NA, or an error. Moreover is.na() behaves differently when evaluated on its own, or as the condition of an if() statement. Here is a function that may make life easier. The goal is NOT to have to pass

Re: [R] list of lists, is this element empty

2014-12-20 Thread Bert Gunter
Boris et. al: Indeed, corner cases are a bear, which is why it is incumbent on any OP to precisely define what they mean by, say, missing, null,empty, etc. Here is an evil example to illustrate the sorts of nastiness that can occur: z - list(a=NULL, b=list(), c=NA) with(z,{ +

Re: [R] list of lists, is this element empty

2014-12-20 Thread Duncan Murdoch
This may be out of context, but on the face of it, this claim is wrong: On 20/12/2014, 1:57 PM, Boris Steipe wrote: Moreover is.na() behaves differently when evaluated on its own, or as the condition of an if() statement. The conditions in an if() statement are not evaluated in special

Re: [R] list of lists, is this element empty

2014-12-20 Thread Boris Steipe
Thanks. This is what I was referring to: x - rep(NA, 3) is.na(x) [1] TRUE TRUE TRUE if (is.na(x)) {print(True)} [1] True Warning message: In if (is.na(x)) { : the condition has length 1 and only the first element will be used You are of course right - the warning is generated by if(), not by