[R] problem selecting rows meeting a criterion
Jim Bouldin
jrbouldin at ucdavis.edu
Tue Aug 11 01:44:10 CEST 2009
What's wrong is I'm trying to select only those rows in which X > Y, but
I'm getting rows in which Y > X and losing some in which X > Y. The row
numbers are not being read as values. Very confusing.
Jim
>
> What's wrong with it? It looks okay to me. If you use
> subset(data, data$X >data$Y)you get the same results. Any chance you're
> reading the row.numbers as values?
>
> BTW "data" is a reserved word in R and it is good practice not to use it
> as a variable name.
>
> My Results
>
> X Y V3
> 3 3 1 2.236068
> 4 4 1 6.324555
> 5 5 1 5.000000
> 6 1 2 8.062258
> 10 5 2 5.656854
> 11 1 3 2.236068
> 12 2 3 9.486833
> 17 2 4 2.236068
> 18 3 4 8.062258
> 24 4 5 5.385165
>
>
> --- On Mon, 8/10/09, Jim Bouldin <jrbouldin at ucdavis.edu> wrote:
>
> > From: Jim Bouldin <jrbouldin at ucdavis.edu>
> > Subject: [R] problem selecting rows meeting a criterion
> > To: r-help at r-project.org
> > Received: Monday, August 10, 2009, 5:49 PM
> >
> > When I try to select only those rows from the following
> > data frame, called
> > "data", in which X > Y
> >
> > X Y V3
> > 2 2 1 8.062258
> > 3 3 1 2.236068
> > 4 4 1 6.324555
> > 5 5 1 5.000000
> > 6 1 2 8.062258
> > 8 3 2 9.486833
> > 9 4 2 2.236068
> > 10 5 2 5.656854
> > 11 1 3 2.236068
> > 12 2 3 9.486833
> > 14 4 3 8.062258
> > 15 5 3 5.099020
> > 16 1 4 6.324555
> > 17 2 4 2.236068
> > 18 3 4 8.062258
> > 20 5 4 5.385165
> > 21 1 5 5.000000
> > 22 2 5 5.656854
> > 23 3 5 5.099020
> > 24 4 5 5.385165
> >
> > using the commands
> > > attach(data)
> > > data2 = data[X >Y,];data2
> >
> > I get this for data2:
> >
> > X Y V3
> > 3 3 1 2.236068
> > 4 4 1 6.324555
> > 5 5 1 5.000000
> > 6 1 2 8.062258
> > 10 5 2 5.656854
> > 11 1 3 2.236068
> > 12 2 3 9.486833
> > 17 2 4 2.236068
> > 18 3 4 8.062258
> > 24 4 5 5.385165
> >
> > Clearly, this is not what I intend but I cannot figure out
> > what I've done
> > wrong. Any help appreciated. Thanks.
> >
> > Jim Bouldin
>
>
>
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Jim Bouldin, PhD
Research Ecologist
Department of Plant Sciences, UC Davis
Davis CA, 95616
530-554-1740
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