[R] logical subsetting, indexes and NAs

[David Winsemius]

On Jan 28, 2012, at 3:45 PM, Dimitris Rizopoulos wrote:

> how about
>
> x[x < 10 & !is.na(x)]
>

Besides this and the which() strategy there is also:

subset(x, x<10)

>
> I hope it helps.
>
> Best,
> Dimitris
>
>
> On 1/28/2012 9:36 PM, Federico Calboli wrote:
>> Dear All,
>>
>> just a quick example:
>>
>>
>>> x  = 1:25
>>> x[12] = NA
>>
>>> x
>>  [1]  1  2  3  4  5  6  7  8  9 10 11 NA 13 14 15 16 17 18 19 20 21  
>> 22 23 24 25
>>
>>> y = x[x<10]
>>> y
>>  [1]  1  2  3  4  5  6  7  8  9 NA
>>
>> Is there any way of NOT getting NA for y = x[x<10]? Similarly
>>
>>> y = x[x<15]
>>> y
>>  [1]  1  2  3  4  5  6  7  8  9 10 11 NA 13 14
>>
>>
>> How do I get rid of the NA (not post hoc)?
>>
>> BW
>>
>> F
>>
>>
>>
>> --
>> Federico C. F. Calboli
>> Neuroepidemiology and Ageing Research
>> Imperial College, St. Mary's Campus
>> Norfolk Place, London W2 1PG
>>
>> Tel +44 (0)20 75941602   Fax +44 (0)20 75943193
>>
>> f.calboli [.a.t] imperial.ac.uk
>> f.calboli [.a.t] gmail.com
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> -- 
> Dimitris Rizopoulos
> Assistant Professor
> Department of Biostatistics
> Erasmus University Medical Center
>
> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
> Tel: +31/(0)10/7043478
> Fax: +31/(0)10/7043014
> Web: http://www.erasmusmc.nl/biostatistiek/
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT