Dear R users, When you do:> x <- rnorm(10) > y <- rnorm(10) > z <- rnorm(10) > a <- data.frame(x,y,z) > a$x[1] 1.37821893 0.21152756 -0.55453182 -2.10426048 -0.08967880 0.03712110 [7] -0.80592149 0.07413450 0.15557671 1.22165341 Why does this not work:> a[a$y>0.5,y] <-1Error in "[<-.data.frame"(`*tmp*`, a$y > 0.5, y, value = 1) : only 0's may be mixed with negative subscripts While this works:> a[a$y>0.5,2] <-1> ax y z 1 1.37821893 -1.0887363 1.7340522 2 0.21152756 -0.7256467 -1.3165373 3 -0.55453182 1.0000000 -2.1116072 4 -2.10426048 -0.4898596 -1.5863823 5 -0.08967880 1.0000000 -0.9139706 6 0.03712110 1.0000000 -1.3004970 7 -0.80592149 -0.7004193 -0.1958059 8 0.07413450 1.0000000 -1.3574303 9 0.15557671 -0.3335407 -2.1991236 10 1.22165341 1.0000000 -0.7576708 For a complex loop I would prefer to reference the right colomn by name, not by number! Now, when the colomns change, I need to check my code to make sure that the right colomns are referenced. Suggestions much appreciated! Thanks in advance, Sander.
When specifying a column name with [ the name must be quoted (unlike when using it with $): a[a$y > 0.5, "y"] <- 1 On 8/4/06, Sander Oom <slist at oomvanlieshout.net> wrote:> Dear R users, > > When you do: > > x <- rnorm(10) > > y <- rnorm(10) > > z <- rnorm(10) > > a <- data.frame(x,y,z) > > a$x > [1] 1.37821893 0.21152756 -0.55453182 -2.10426048 -0.08967880 0.03712110 > [7] -0.80592149 0.07413450 0.15557671 1.22165341 > > Why does this not work: > > a[a$y>0.5,y] <-1 > Error in "[<-.data.frame"(`*tmp*`, a$y > 0.5, y, value = 1) : > only 0's may be mixed with negative subscripts > > While this works: > > a[a$y>0.5,2] <-1 > > > a > x y z > 1 1.37821893 -1.0887363 1.7340522 > 2 0.21152756 -0.7256467 -1.3165373 > 3 -0.55453182 1.0000000 -2.1116072 > 4 -2.10426048 -0.4898596 -1.5863823 > 5 -0.08967880 1.0000000 -0.9139706 > 6 0.03712110 1.0000000 -1.3004970 > 7 -0.80592149 -0.7004193 -0.1958059 > 8 0.07413450 1.0000000 -1.3574303 > 9 0.15557671 -0.3335407 -2.1991236 > 10 1.22165341 1.0000000 -0.7576708 > > For a complex loop I would prefer to reference the right colomn by name, > not by number! Now, when the colomns change, I need to check my code to > make sure that the right colomns are referenced. > > Suggestions much appreciated! > > Thanks in advance, > > Sander. > > ______________________________________________ > R-help at stat.math.ethz.ch 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. >
you need to use quotes, i.e.,
a[a$y > 0.5, "y"] <- 1
you can also use
a$y[a$y > 0.5] <- 1
I hope it helps.
Best,
Dimitris
----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm
----- Original Message -----
From: "Sander Oom" <slist at oomvanlieshout.net>
To: <r-help at stat.math.ethz.ch>
Sent: Friday, August 04, 2006 1:48 PM
Subject: [R] Data frame referencing?
> Dear R users,
>
> When you do:
>> x <- rnorm(10)
>> y <- rnorm(10)
>> z <- rnorm(10)
>> a <- data.frame(x,y,z)
>> a$x
> [1] 1.37821893 0.21152756 -0.55453182 -2.10426048 -0.08967880
> 0.03712110
> [7] -0.80592149 0.07413450 0.15557671 1.22165341
>
> Why does this not work:
>> a[a$y>0.5,y] <-1
> Error in "[<-.data.frame"(`*tmp*`, a$y > 0.5, y, value = 1)
:
> only 0's may be mixed with negative subscripts
>
> While this works:
>> a[a$y>0.5,2] <-1
>
>> a
> x y z
> 1 1.37821893 -1.0887363 1.7340522
> 2 0.21152756 -0.7256467 -1.3165373
> 3 -0.55453182 1.0000000 -2.1116072
> 4 -2.10426048 -0.4898596 -1.5863823
> 5 -0.08967880 1.0000000 -0.9139706
> 6 0.03712110 1.0000000 -1.3004970
> 7 -0.80592149 -0.7004193 -0.1958059
> 8 0.07413450 1.0000000 -1.3574303
> 9 0.15557671 -0.3335407 -2.1991236
> 10 1.22165341 1.0000000 -0.7576708
>
> For a complex loop I would prefer to reference the right colomn by
> name,
> not by number! Now, when the colomns change, I need to check my code
> to
> make sure that the right colomns are referenced.
>
> Suggestions much appreciated!
>
> Thanks in advance,
>
> Sander.
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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.
>
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