[R] Subsetting a data.frame degenerates at one column?
John Kane
jrkrideau at yahoo.ca
Sat Feb 9 17:35:35 CET 2008
I think I understand this. Try
str(input) and you will see that input$disk2 in a
vector. You can force a data.frame using
data.frame(input(,targets))
--- "Allen S. Rout" <asr at ufl.edu> wrote:
>
> Greetings.
>
> At the moment, I'm applying R to some AIX 'nmon'
> output, trying to get
> a handle on some disk performance metrics. In case
> anyone's
> interested:
>
> http://docs.osg.ufl.edu/tsm/pdf/
>
> some of them are more edifying than others. (ahem)
>
> I'm trying to develop a somewhat general framework
> for plotting these
> measures, in the hopes that it's of some use to
> people other than me.
> One obstacle I encounter is that, when I select one
> column out of a
> data.frame, the result is no longer a data.frame.
> So, say I've got,
> in data frame 'input'
>
> disk1 disk2 disk3 disk4
> T0000 0 1 0 4
> T0001 0 1 0 5
> T0002 0 1 0 5
> T0003 0 2 0 4
> T0004 0 2 0 3
> T0005 0 1 0 3
> T0006 0 0 0 3
>
> and somewhere I've noted a list
>
> targets <- c('disk2','disk3')
>
> I can say
>
> input[,targets]
> disk2 disk3
> T0000 1 0
> T0001 1 0
> T0002 1 0
> T0003 2 0
> T0004 2 0
> T0005 1 0
> T0006 0 0
>
> but if
>
> targets <- c('disk2')
> input[,targets]
> [1] 1 1 1 2 2 1 0
>
> Ick.
>
> I've been reading through the indexing and
> data.frame docs, and remain
> unsatisfied so far. Where is my thinking going
> wrong?
>
>
>
> - Allen S. Rout
>
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