>>>>> "SH" == Schalk Heunis <schalk.heu...@enerweb.co.za>
>>>>> on Thu, 17 Sep 2009 11:15:16 +0200 writes:
SH> I think this is what you want:
>> df <- data.frame(x1=1:11,x2=2:12,x3=3:13,y=4:14)
>> grep('^x',names(df))
SH> [1] 1 2 3
SH> The returned indexes refer to the column positions, so you could do:
>> names(df)[grep('^x',names(df))]
SH> [1] "x1" "x2" "x3"
yes, or slightly more elegant and efficient
> grep('^x',names(df), value = TRUE)
[1] "x1" "x2" "x3"
SH> or
>> df[,grep('^x',names(df))]
SH> x1 x2 x3
SH> 1 1 2 3
SH> 2 2 3 4
SH> 3 3 4 5
SH> 4 4 5 6
SH> 5 5 6 7
SH> 6 6 7 8
SH> 7 7 8 9
SH> 8 8 9 10
SH> 9 9 10 11
SH> 10 10 11 12
SH> 11 11 12 13
SH> HTH
SH> Schalk Heunis
SH> On Thu, Sep 17, 2009 at 5:03 AM, Peng Yu <pengyu...@gmail.com> wrote:
>> Hi,
>>
>> data.frame(x1=1:11,x2=2:12,x3=3:13,y=4:14)
>>
>> I want to extract all the columns that with the name 'x?'. Is there a
>> general way to do this in R?
>>
>> Regards,
>> Peng
>>
>> ______________________________________________
>> R-help@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.
>>
SH> [[alternative HTML version deleted]]
SH> ______________________________________________
SH> R-help@r-project.org mailing list
SH> https://stat.ethz.ch/mailman/listinfo/r-help
SH> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
SH> and provide commented, minimal, self-contained, reproducible code.
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