Hi Martin,
On 01/26/2015 04:45 AM, Martin Maechler wrote:
Jim Lemon <drjimle...@gmail.com>
on Mon, 26 Jan 2015 11:21:03 +1100 writes:
> Hi Allen, How about this:
> sum_w_NA<-function(x) ifelse(all(is.na(x)),NA,sum(x,na.rm=TRUE))
Excuse, Jim, but that's yet another "horrible misuse of ifelse()"
John Fox's reply *did* contain the "proper" solution
if (all(is.na(x))) NA else sum(x, na.rm=TRUE)
The ifelse() function should never be used in such cases.
Read more after googling
"Do NOT use ifelse()"
-- include the quotes in your search --
or directly at
http://stat.ethz.ch/pipermail/r-help/2014-December/424367.html
Interesting. You could have added the following item to your list:
4. less likely to play strange tricks on you:
> ifelse(TRUE, a <- 2L, a <- 3L)
[1] 2
> a
[1] 3
Yeah I've seen people using ifelse() that way and being totally
confused...
Cheers,
H.
Yes, this has been on R-help a month ago..
Martin
> On Mon, Jan 26, 2015 at 10:21 AM, Allen Bingham
> <aebingh...@gmail.com> wrote:
>> I understand that in order to get the sum function to
>> ignore missing values I need to supply the argument
>> na.rm=TRUE. However, when summing numeric values in which
>> ALL components are "NA" ... the result is 0.0 ... instead
>> of (what I would get from SAS) of NA (or in the case of
>> SAS ".").
>>
>> Accordingly, I've had to go to 'extreme' measures to get
>> the sum function to result in NA if all arguments are
>> missing (otherwise give me a sum of all non-NA elements).
>>
>> So for example here's a snippet of code that ALMOST does
>> what I want:
>>
>>
>>
SumValue<-apply(subset(InputDataFrame,!is.na(Variable.1)|!is.na(Variable.2),
>> select=c(Variable.1,Variable.2)),1,sum,na.rm=TRUE)
>>
>> In reality this does NOT give me records with NA for
>> SumValue ... but it doesn't give me values for any
>> records in which both Variable.1 and Variable.2 are NA
>> --- which is "good enough" for my purposes.
>>
>> I'm guessing with a little more work I could come up with
>> a way to adapt the code above so that I could get it to
>> work like SAS's sum function ...
>>
>> ... but before I go that extra mile I thought I'd ask
>> others if they know of functions in either base R ... or
>> in a package that will better mimic the SAS sum function.
>>
>> Any suggestions?
>>
>> Thanks. ______________________________________ Allen
>> Bingham aebingh...@gmail.com
>>
>> ______________________________________________
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>> commented, minimal, self-contained, reproducible code.
> ______________________________________________
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and
> more, see https://stat.ethz.ch/mailman/listinfo/r-help
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> http://www.R-project.org/posting-guide.html and provide
> commented, minimal, self-contained, reproducible code.
______________________________________________
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--
Hervé Pagès
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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