[R] na.action in xtabs - how to include NAs?

[David L Carlson]

If you are going to do this routinely or with many factors, you can build NA into each of the factors, but that will affect other operations:

> xNA <- lapply(x, factor, exclude=NULL)
> xtabs(~a+b, xNA)
      b
a      2 3 4 <NA>
  1    0 0 0    1
  2    1 0 0    0
  3    0 1 0    0
  <NA> 0 0 1    0

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Dimitri Liakhovitski
Sent: Wednesday, September 30, 2015 10:22 AM
To: William Dunlap
Cc: r-help
Subject: Re: [R] na.action in xtabs - how to include NAs?

Thank you very much, Bill - it worked.
Wow, that's very wordy!

On Wed, Sep 30, 2015 at 11:09 AM, William Dunlap <wdunlap at tibco.com> wrote:
> Try both na.action=na.pass and exclude=NULL, the first is for
> xtabs' call to model.frame and the second for when it prepares
> the data from model.frame's output for a call to table.
>
> xtabs(formula = ~a + b, data = x, na.action = na.pass, exclude = NULL)
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Wed, Sep 30, 2015 at 7:56 AM, Dimitri Liakhovitski
> <dimitri.liakhovitski at gmail.com> wrote:
>> Please help:
>>
>> # I have a data frame x:
>> x <- data.frame(a = c(1:3, NA), b = c(NA, 2:4))
>>
>> # I run a cross-tab keeping NAs, like this:
>> table(x[c("a", "b")], useNA = "ifany")
>>
>> # I want to reproduce it using xtabs, but it ignores NAs:
>> xtabs(~ a + b, x)
>>
>> # I can't figure out how to force xtabs to include NAs.
>> # All my attempts below fail to include NAs:
>> xtabs(~ a + b, x, na.action(na.pass))
>> xtabs(~ a + b, x, na.action = "na.pass")
>> xtabs(~ a + b, x, na.action(na.pass(x)))
>> xtabs(~ a + b, x, exclude = NULL)
>>
>> Thank you for your hints!
>> --
>> Dimitri Liakhovitski
>>
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-- 
Dimitri Liakhovitski

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