# [R] Column naming mystery

Søren Højsgaard Soren.Hojsgaard at agrsci.dk
Tue Aug 28 14:49:05 CEST 2007

```I'd be glad to help, but I don't think I understand the problem. Here's what I get:
> x <- as.data.frame(matrix(ncol=3,seq(1,12),dimnames=list(c(),c("hh","total","total.inf"))))
> x
hh total total.inf
1  1     5         9
2  2     6        10
3  3     7        11
4  4     8        12
> summaryBy(total+total.inf~hh,x,FUN=sum)
hh total.sum total.inf.sum
1  1         5             9
2  2         6            10
3  3         7            11
4  4         8            12

Looks as expected to me.

Regards
Søren Højsgaard

-----Oprindelig meddelelse-----
Fra: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] På vegne af Werner Wernersen
Sendt: 27. august 2007 15:21
Til: r-help at stat.math.ethz.ch
Emne: Re: [R] Column naming mystery

Sorry that the problem description was not sufficient.
Here is a self-contained code replicating the problem:

require(doBy)
x <-
as.data.frame(matrix(ncol=3,seq(1,12),dimnames=list(c(),c("hh","total","total.inf"))))
summaryBy(total+total.inf~hh,x,FUN=sum)

What surprises me are the zeros in the resulting total.sum column. The problem remains if total.inf is renamed to totalinf or total_inf but not if renamed to ttotal.inf .

Can anyone explain to me what the rules for naming columns are so that I can avoid such mistakes in the future?

Thanks a lot!

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