[R] Selecting all rows of factors which have at least one positive value?

[David Winsemius]

I think the unique function is superfluous:

 > x[x$X1 %in% x$X1[x$X2==1], ]
    X1 X2
1  11  0
2  11  0
3  11  0
4  11  1
8  13  0
9  13  1
10 13  1

--  

David Winsemius

On Apr 2, 2009, at 12:43 PM, Patrizio Frederic wrote:

> or the exactly equivalent form:
>
> x[x$X1 %in% unique(x[x$X2>0,"X1"]), ]
>
> Patrizio
>
> 2009/4/2 Nutter, Benjamin <NutterB at ccf.org>:
>> x <-
>> data.frame(matrix(c(rep(11,4),rep(12,3),rep(13,3),rep(0,3), 
>> 1,rep(0,4),re
>> p(1,2)),ncol=2))
>>
>> id.keep <- unique(subset(x,X2>0)$X1)
>>
>> x2 <- subset(x,X1 %in% id.keep)
>>
>> x2
>>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org 
>> ]
>> On Behalf Of Stephan Lindner
>> Sent: Thursday, April 02, 2009 11:26 AM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] Selecting all rows of factors which have at least one
>> positive value?
>>
>> Dear all,
>>
>> I'm trying to select from a dataframe all rows which correspond to a
>> factor (the id variable) for which there exists at least one positive
>> value of a certain variable. As an example:
>>
>> x <-
>> data.frame(matrix(c(rep(11,4),rep(12,3),rep(13,3),rep(0,3), 
>> 1,rep(0,4),re
>> p(1,2)),ncol=2))
>>
>>> x
>>
>>
>>   X1 X2
>> 1  11  0
>> 2  11  0
>> 3  11  0
>> 4  11  1
>> 5  12  0
>> 6  12  0
>> 7  12  0
>> 8  13  0
>> 9  13  1
>> 10 13  1
>>
>>
>> and I want to select all rows pertaining to factor levels of X1 for
>> which exists at least one "1" for X2. To be clear, I want rows 1:4
>> (since there exists at least one observation for X1==11 for which
>> X2==1) and rows 8:10 (likewise).
>>
>> It is easy to obtain the corresponding factor levels (i.e.,
>> unique(x$X1[x$X2==1])), but I got stalled selecting the corresponding
>> rows. I tried grep, but then I have to loop and concatenate the
>> resulting vector. Any ideas?
>>
>>
>> Thanks a lot!
>>
>>
>>        Stephan
>>
>>
>>
>>
>>
>> --
>> -----------------------
>> Stephan Lindner
>> University of Michigan
>>
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>>
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>
> ______________________________________________
> 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
Heritage Laboratories
West Hartford, CT